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Throwback tax explained: Rules for trusts, foreign trusts, and state-level obligations in 2026
If you are a US beneficiary of a trust – especially a foreign trust – and you receive a distribution that includes income accumulated over prior years, the IRS may tax you as if that income had been paid out in the years it was earned. That is the core idea behind the throwback tax.
This article walks through the federal rules under IRC Sections 665–668, explains how foreign trusts face the harshest treatment, covers state-level rules in California and Illinois, and outlines the reporting obligations and planning strategies every US beneficiary should understand.
What is the throwback tax? A plain-English overview
The throwback tax is a federal – and in some states, state-level – mechanism that taxes accumulated trust income when it is finally distributed to a beneficiary, as if it had been distributed in the year it was earned.
Here is how the basic mechanism works:
- A trust earns income but does not distribute it. That income stays inside the trust as undistributed net income – UNI.
- The trust later makes a large distribution that exceeds its current-year income. The excess is treated as an “accumulation distribution” under IRC Sections 665–668.
- The IRS looks back at the prior years when that income was earned and calculates tax as though the beneficiary had received it in those years.
- The result is a tax bill – sometimes accompanied by an interest charge – that can be significantly larger than what the beneficiary would have owed on a simple current-year distribution.
Why the throwback tax exists
Trusts, particularly foreign trusts, can be used to defer US income tax for years or even decades. The throwback rules close that gap by ensuring accumulated income is eventually taxed at the beneficiary's historical rates.
Distributable net income and the other terms behind these rules are defined in Internal Revenue Code Section 643.
See our TFX guide to foreign non-grantor trusts for more on how these trusts are structured and taxed.
How the throwback rule works: IRC Sections 665–668
Under IRC Section 667, the beneficiary – not the trust – pays the throwback tax in the year of distribution, based on rates from the years income was accumulated. The calculation follows a four-step process under IRC Sections 665–668:
- Identify undistributed net income – UNI – from prior years. For each prior year, UNI equals distributable net income – DNI – minus actual distributions made minus taxes attributable to that income, under IRC §665(a).
- Allocate the accumulation distribution across those prior years. The distribution is allocated oldest-year-first (FIFO), with each year's allocation capped at that year's UNI, under IRC §666.
- Compute the hypothetical tax using the beneficiary's actual tax rates. The IRS uses an averaging method: it takes the beneficiary's taxable income for the five preceding years, drops the highest and lowest, and averages the remaining three to determine the applicable rate, under IRC §667.
- Apply the interest charge under Section 668. For foreign trusts, an interest charge is added based on the §6621 underpayment rate for each year income was accumulated. This charge approximates the time-value benefit the beneficiary gained from deferral.
The beneficiary reports the resulting tax on Form 4970 – Tax on Accumulation Distribution of Trusts –, attached to Form 1040, for accumulation distributions from certain pre-March 1, 1984 domestic trusts.
For distributions from foreign trusts, the throwback tax and interest charge are reported on Form 3520 instead. Form 4970 isn't filed separately in that case, per the IRS Instructions for Form 3520, though its computation is attached to Form 3520 as a worksheet.
Foreign non-grantor trusts can't qualify for the “qualified trust” exemption under Internal Revenue Code Section 665(c), so every accumulation distribution from a foreign trust triggers the full throwback calculation.
Mismatches in how foreign income is timed on a US return can inflate the trust's UNI balance and amplify throwback exposure.
Key terms you must know: DNI, UNI, and accumulation distributions
Misunderstanding the difference between DNI and UNI is the single most common reason US beneficiaries are blindsided by a throwback tax bill.
These three terms form the foundation of the throwback rules under Subchapter J of the Internal Revenue Code:
- Distributable net income – DNI – is the ceiling on what a trust can deduct for distributions and what a beneficiary must include in income for a given year. DNI is essentially the trust's taxable income, adjusted for certain items like capital gains and tax-exempt interest.
- Undistributed net income – UNI – is DNI that was not distributed in the year it was earned. Under IRC §665(a), UNI equals DNI minus distributions actually made, minus taxes the trust paid on that income. UNI accumulates year over year inside the trust.
- Accumulation distribution is any distribution that exceeds the trust's current-year DNI. Under IRC §665(b), the excess is treated as coming from prior years' UNI – triggering the throwback rules.
How these terms interact in practice
Consider this simplified example:
- A trust earns $100,000 of DNI in a given year, distributes nothing, and pays $20,000 in tax. That year's UNI is $80,000.
- Several years later, the trust distributes $500,000 in a year when its DNI is only $50,000.
- The remaining $450,000 is an accumulation distribution – subject to throwback tax under §§665–668.
The $450,000 is then allocated across the prior years that generated the UNI, oldest year first, and tax is computed at the beneficiary's historical rates for each of those years.
The IRS's own practice unit on foreign non-grantor trust taxation walks through how these computations work across multiple accumulation years.
Throwback tax on foreign trusts: the harshest application
Unlike domestic trusts, foreign non-grantor trusts have no exception to the throwback rules, making even modest accumulation distributions potentially very costly for US beneficiaries.
The Taxpayer Relief Act of 1997 effectively repealed the federal throwback rules for most domestic trusts, but Congress deliberately excluded foreign trusts from that relief.
This means every dollar of UNI that has accumulated inside a foreign non-grantor trust is subject to throwback tax when distributed to a US beneficiary.
There is no minimum threshold and no de minimis exception – even a distribution of a few thousand dollars can trigger the full four-step calculation.
What makes foreign trusts particularly punitive
Several factors stack against US beneficiaries of foreign trusts:
- No exception to the throwback rules. Unlike domestic trusts, foreign non-grantor trusts cannot qualify for the “qualified trust” exemption under IRC §665(c).
- The Section 668 interest charge. An additional interest charge – based on the §6621 underpayment rate with daily compounding for post-1995 years – is added on top of the throwback tax. Because many foreign trusts accumulate income for decades, the interest alone can rival the underlying tax.
- Harsh penalties for non-filing. US beneficiaries must report distributions on Form 3520 – Annual Return to Report Transactions with Foreign Trusts and Receipt of Certain Foreign Gifts. Failure to file triggers a penalty equal to the greater of $10,000 or 35% of the gross reportable amount under IRC §6677.
Without these records, the IRS may treat the entire distribution as an accumulation distribution – the worst possible outcome.
The interest charge on throwback tax: Section 668 explained
The Section 668 interest charge is not deductible and can easily exceed the throwback tax itself when income has been accumulating inside a foreign trust for a decade or more.
Under IRC §668, this charge approximates the time-value benefit the beneficiary received by deferring tax through the trust.
The interest rate is based on the §6621 underpayment rate. For accumulation years before January 1, 1996, the rate is 6% without compounding.
For years after 1995, the §6621 rate applies with daily compounding – which means the effective charge grows significantly for each additional year of deferral.
Example: how the interest charge adds up
A US beneficiary receives a $300,000 accumulation distribution from a foreign trust that accumulated income over 15 years:
- Throwback tax – computed using the beneficiary's historical rates under §667 – comes to approximately $75,000.
- Section 668 interest charge, compounding over those 15 years, adds another $40,000–$60,000.
- Total tax bill: $115,000–$135,000 on a $300,000 distribution.
There is one cap: the combined throwback tax and interest charge cannot exceed the total accumulation distribution itself. For foreign trust distributions, the beneficiary reports the interest charge together with the throwback tax on Form 3520.
Which states have a throwback rule? A state-by-state overview
Not all states follow the federal throwback framework, and the throwback rule state tax treatment varies significantly by state. The states that do impose their own rules often apply unique variations that can catch beneficiaries off guard.
California imposes the broadest state throwback tax on accumulation distributions, New York imposes a narrower one on distributions from exempt resident trusts, and Illinois likely applies one; most other states do not.
| State | Throwback rule applies | Key feature |
|---|---|---|
| California | Yes | Taxes accumulation distributions to resident beneficiaries under R&TC §17745; applies even when the trust has no California connection |
| Illinois | Likely yes | Taxes trust distributions to resident beneficiaries under general income tax provisions; statutory basis less clearly defined than California's |
| New York | Yes, narrow | Imposes a throwback tax under N.Y. Tax Law §612(b)(40) on accumulation distributions from an “exempt resident trust” – a non-grantor trust with no New York trustees, property, or source income – to a New York resident beneficiary age 21 or older, reported on Form IT-205-J; reaches income accumulated in tax years beginning on or after January 1, 2014, that New York hasn't already taxed |
| Texas | No state income tax | No throwback rule applicable |
| Florida | No state income tax | No throwback rule applicable |
| Nevada | No state income tax | No throwback rule applicable |
California throwback tax: how California taxes trust accumulation distributions
California is one of the most aggressive states in taxing trust accumulation distributions, applying its throwback rules even when the trust itself has no California connection.
California taxes accumulation distributions made to California resident beneficiaries under R&TC §17745, regardless of where the trust was established or administered. Which computation applies depends on whether the trust issued you a Schedule J (541).
If it did, FTB Form 5870A directs you to compute the tax using the federal IRC §667 averaging method. If it didn't because your interest was contingent and the trust paid no tax on the accumulated income, R&TC §17745(b) applies, and you compute the tax under R&TC §17745(d) instead.
California's throwback rules differ from the federal framework in several important ways:
- California applies its own tax rates, including the top marginal rate on ordinary income, which currently reaches 13.3% (2025) once the 1% tax on income over $1 million is added to the 12.3% top bracket. If the trust issued you a Schedule J (541), FTB Form 5870A, Tax on Accumulation Distribution of Trusts, directs you to the same federal averaging method used for IRC §667. If no Schedule J (541) was issued because your interest was contingent and the trust paid no tax on the accumulated income, California instead computes the tax under R&TC §17745(d), spreading the income ratably over the distribution year and the five preceding tax years, or over the shorter period the trust accumulated it.
- No conformity to federal exceptions. Under R&TC §17779, California doesn't apply IRC Sections 665 through 668 to the distributions described in R&TC §17745(b), so California computes its own tax on those accumulation distributions instead of following the federal rules.
- Noncontingent beneficiary status matters. Under Cal. Code Regs. tit. 18, §17742(b), a beneficiary is treated as a noncontingent beneficiary if their interest in the trust isn't subject to a condition precedent; a beneficiary whose interest depends on a condition being met is generally treated as contingent.
- California income taxation of trusts depends on this distinction – it determines how income is split between the trust entity and the individual beneficiary.
- The CA throwback rule under R&TC §17745(b) applies to a contingent beneficiary who is a California resident when the distribution is received. R&TC §17745(d) computes the tax by including the income ratably over the distribution year and the five preceding tax years, or over the period the trust actually accumulated the income for you as a contingent beneficiary, whichever is shorter. This isn't simply a count of the years you lived in California, so don't assume income accumulated before you moved to the state is automatically excluded. Confirm the exact computation against the trust's accumulation history.
The California trust tax burden can be substantial. A beneficiary receiving a large accumulation distribution may owe both federal throwback tax – including the §668 interest charge for foreign trusts – and California throwback tax at rates up to 13.3% – all on the same distribution.
The California Lawyers Association published a detailed analysis of how the California throwback tax applies to distributions of previously untaxed accumulated trust income.
See our article on California's nonresident income tax rules for how California taxes other income types after you leave the state.
The Illinois throwback rule: what Illinois residents need to know
Illinois residents who receive large lump-sum distributions from family trusts should always verify whether the trust accumulated income during years they lived outside Illinois, as that income may be subject to Illinois throwback tax upon distribution.
While the statutory framework is less explicitly defined than California's, 35 ILCS 5/306 addresses allocation and apportionment of trust income but does not contain a standalone throwback statute.
Illinois generally taxes trust distributions received by Illinois resident beneficiaries as current-year income. A trust distribution to a nonresident beneficiary, by contrast, is taxed by Illinois only on the portion attributable to Illinois-source income.
The practical effect is similar to a throwback rule. If a trust accumulated income during years the beneficiary lived in another state and then distributes that income after the beneficiary moves to Illinois, the distribution may be taxed by Illinois in the year received.
Illinois's flat income tax rate of 4.95% (2025) applies to the full amount.
Beneficiaries should retain trust accounting records showing when income was earned and when it was distributed.
Illinois Schedule NR, Nonresident Computation of Fiduciary Income, is required when the trust or estate itself is a nonresident of Illinois, to compute the Illinois-source share of its income – it isn't triggered by having both resident and nonresident beneficiaries. A trust reports each beneficiary's share of income on Schedule K-1-T.
Throwback and throwout rules: understanding the difference
The throwback rule increases a company's in-state sales factor, while the throwout rule reduces the denominator – both result in higher state taxable income, but through opposite mechanisms.
It is important to understand that in the state corporate tax context, “throwback” and “throwout” refer to sales apportionment rules – a different concept from the throwback tax on trust accumulation distributions discussed in the rest of this article.
- Throwback rule – corporate context: When a company sells tangible personal property into a state that does not tax the seller, the sale is “thrown back” to the seller's home state and included in that state's sales factor numerator. This increases the share of income apportioned to the home state.
- Throwout rule – corporate context: Instead of reassigning the sale to the seller's state, the sale is removed from the sales factor denominator entirely. The effect is similar – a higher percentage of income apportioned to taxing states – but the mechanism differs.
Both rules exist because states do not want companies to reduce their apportioned income by directing sales into states with no income tax.
These rules aren't universal. As of January 1, 2024, 19 states and the District of Columbia applied a throwback rule, and Maine applied a throwout rule – the rest applied neither. States revisit these rules periodically – Arkansas, for example, has moved to phase out its throwback rule – so confirm current treatment for a specific state before relying on this count.
If you are reading this article because of a trust distribution, the trust-related throwback rules under IRC §§665–668 are what apply to your situation. The corporate throwback and throwout rules affect businesses with multi-state operations.
Throwback sales and the Joyce rule: state corporate tax context
Businesses operating across multiple states must understand whether each state uses the throwback rule, the throwout rule, or neither, because the choice dramatically affects the state sales factor and overall state tax liability.
What are throwback sales?
Throwback sales are sales of tangible personal property that are thrown back to the seller's state when the purchaser's state does not tax the seller.
For example, if a California company ships goods to a customer in Nevada – which has no corporate income tax – California's throwback rule assigns that sale to California's sales factor, increasing the company's California taxable income.
The Joyce rule
The Joyce rule tax treatment, from the California State Board of Equalization decision in Appeal of Joyce, Inc., holds that the sales factor is computed entity-by-entity rather than on a combined unitary basis.
In a combined reporting group, each entity's sales are apportioned based on that entity's own nexus with each state – not the group's collective presence.
States applying the alternative Finnigan rule look at the unitary group's combined nexus, which can produce a different apportionment result.
The domestic trust exception and taxes already paid by the trust
Most domestic non-grantor trusts are now exempt from the federal throwback rules. The Taxpayer Relief Act of 1997 effectively repealed these rules for domestic trusts by expanding the “qualified trust” exception under IRC §665(c).
As a result, distributions from domestic trusts created after March 1, 1984, generally do not trigger throwback tax – regardless of how much UNI has accumulated.
The narrow exceptions that still apply to domestic trusts:
- Pre-March 1, 1984 trusts: Domestic trusts created before this date are not treated as “qualified trusts” and remain subject to the throwback rules for trusts. These trusts must still use Form 4970 to compute any throwback tax owed.
- Formerly foreign trusts: A trust that was once classified as a foreign trust and later became a domestic trust may still be subject to throwback rules for UNI accumulated during the years it was foreign.
- Multiple trust arrangements: Trusts structured to circumvent the throwback rules may be subject to them under anti-abuse provisions.
Under Internal Revenue Code Section 665(a), undistributed net income is reduced by taxes the trust already paid on that income.
This prevents double taxation of income the trust was taxed on when it is later distributed.
Charitable remainder trusts and pooled income funds are tax-exempt vehicles governed by their own IRS rules and generally do not accumulate the kind of taxable beneficiary income the throwback rules target.
Grantor trust rules: why grantor trusts avoid the throwback tax
Structuring a foreign trust as a grantor trust is one of the most effective ways to eliminate throwback tax exposure, but it requires careful compliance with the grantor trust rules under IRC Sections 671–679 and annual reporting on Form 3520-A.
If a trust qualifies as a grantor trust, all income is taxed directly to the grantor each year – there is no accumulation of undistributed net income at the trust level. Because UNI never builds up, no accumulation distribution can occur, and the throwback rules simply do not apply.
IRC §679 is particularly relevant for expats. It provides that when a US person transfers property to a foreign trust that has at least one US beneficiary, the US transferor is treated as the owner – the grantor – of the trust for income tax purposes.
This means the transferor reports and pays tax on all trust income annually, which eliminates the deferral that gives rise to throwback tax.
Exceptions to §679: transfers at death and fair market value transfers
Transfers at death aren't subject to §679. Transfers for fair market value are excluded only to the extent the transferor actually receives consideration equal to that value.
If the transferor is related to the trust, the grantor, or a beneficiary, any note given as consideration must meet all six “qualified obligation” conditions in Treasury Regulation §1.679-4(d):
- a written agreement
- a term of five years or less
- all payments made in US dollars
- a yield to maturity between 100% and 130% of the applicable federal rate in effect on the note's issue date
- the transferor's written agreement extending the assessment period for related income and transfer taxes to a date at least three years after the note's maturity
- annual Form 3520 reporting while the note is outstanding
A note that doesn't meet these conditions is disregarded, and the transfer is treated as if no consideration were paid. Where an exception does apply, the trust may be classified as a non-grantor trust, and the throwback rules apply in full.
Reporting requirements for grantor trusts
A foreign grantor trust must file Form 3520-A annually, and the US owner reports all trust income on their personal return each year.
The annual compliance burden is real, but it is far less costly than the throwback tax and §668 interest charge that arise when income accumulates undistributed inside a non-grantor trust.
How expats and returning Americans are affected by throwback tax
Returning expats who receive trust distributions in their first year back in the US are among the most common throwback tax victims – the tax bill can arrive before they have even filed their first US resident return.
Expats face unique throwback tax exposure because they are often beneficiaries of foreign family trusts that accumulated income during years spent abroad.
A common TFX client scenario
An American lived in the UK for 12 years and was a beneficiary of a family trust established in Jersey. The trust accumulated income throughout that period, reinvesting dividends and interest rather than making distributions.
When the client returned to the US and received a lump-sum distribution of £400,000 – approximately $500,000 –, the throwback tax calculation applied to all 12 years of accumulated income. The combined federal tax bill exceeded $150,000 – on top of any state taxes owed.
Why returning expats are especially vulnerable
- Many expats do not realize they have US reporting obligations for foreign trusts while living abroad.
- They may not have filed Form 3520 in prior years, and the trust may not have filed Form 3520-A.
- The distribution triggers both the throwback tax and potential penalties for prior-year non-compliance.
- The throwback calculation depends on the beneficiary's US filing status in each accumulation year – gaps in filing history complicate the §667 computation.
Strategies to minimize or avoid throwback tax rules
Proactive planning before a distribution is made is far more effective than trying to reduce throwback tax after the fact, because the interest charge under Section 668 begins accruing from the year income was earned.
The following five strategies can reduce or eliminate throwback tax exposure:
- Convert the foreign trust to grantor trust status under IRC §679. If a US person is treated as the owner of the trust, all income is taxed currently to the grantor. No UNI accumulates, and no throwback tax arises on distributions.
- Distribute income currently each year. Annual distributions equal to DNI eliminate UNI and prevent throwback tax from ever arising. This is the simplest strategy, but it requires the trustee to cooperate and the trust instrument to permit current distributions.
- Time distributions across multiple tax years. Spreading distributions over several years can reduce the hypothetical tax rate under §667 by keeping each year's accumulation distribution smaller. This does not eliminate the throwback tax, but it can lower the effective rate.
- Review how much of the trust's undistributed net income reflects tax the trust already paid. Under Section 665(a), that portion is excluded from the accumulation distribution calculation, so understanding it can help quantify actual throwback tax exposure.
- Evaluate whether domestic trust restructuring is feasible. In some cases, a foreign trust can be restructured or migrated to US domestic trust status. Once the trust qualifies as a domestic trust, future accumulation distributions may be exempt from the throwback rules.
Foreign taxes the trust paid on accumulated income may offset your US throwback tax through the foreign tax credit, reducing the net amount owed.
Trust distribution reporting for US beneficiaries: a compliance checklist
US beneficiaries of foreign trusts face a multi-form compliance burden that goes well beyond simply reporting the distribution as income on Form 1040. Missing any of these requirements can result in penalties, so treat this as a minimum checklist:
- Form 3520 – File if you received a distribution from a foreign trust, or if you had certain other transactions with a foreign trust during the year. Due with your income tax return – including extensions. Penalties under IRC §6677: the greater of $10,000 or 35% of the gross reportable amount. Certain tax-favored foreign trusts may qualify for simplified reporting.
- Form 4970 – Attach to your Form 1040 to compute the throwback tax and Section 668 interest charge on accumulation distributions from pre-March 1, 1984 domestic trusts. For foreign trust distributions, the throwback calculation is done through Form 3520 instead.
- Form 8938 – Report the trust interest as a specified foreign financial asset if its value exceeded $200,000 (single) or $400,000 (married filing jointly) on the last day of tax year 2025, or $300,000 (single) or $600,000 (married filing jointly) at any point during tax year 2025 – whichever threshold applies to your filing status.
- State-level filings – Check whether your state – especially California, New York, or Illinois – imposes a separate state throwback tax. California beneficiaries compute the tax on FTB Form 5870A. An Illinois trust that is itself a nonresident files Schedule NR to compute its Illinois-source income; each beneficiary's share is reported on Schedule K-1-T regardless of the beneficiary's own residency.
- Trust accounting records – Retain records showing UNI for each prior year the trust accumulated income. Without these records, the IRS may treat the entire distribution as taxable under the throwback rules.
US taxpayers abroad face a broader set of filing requirements than domestic filers, particularly when foreign trusts, PFICs, and foreign financial accounts are involved.
Penalties for non-compliance: what happens if you ignore throwback tax
The penalty exposure for ignoring throwback tax obligations is severe, and it compounds over time:
- Form 3520 penalty: Failure to report a foreign trust distribution triggers a penalty equal to the greater of $10,000 or 35% of the gross reportable amount under IRC §6677. For large distributions, this penalty alone can be tens of thousands of dollars.
- Underpayment penalties: Failure to pay the throwback tax results in standard underpayment penalties on top of the tax itself.
- Section 668 interest charge: The interest charge uses the §6621 underpayment rate with daily compounding for post-1995 years and is not deductible. Ignoring a throwback tax obligation for even a few years can cause the interest to rival or exceed the original tax.
Taxpayers who non-willfully failed to report foreign trust distributions in prior years generally use the IRS Streamlined Filing Compliance Procedures to catch up.
The Offshore Voluntary Disclosure Program closed in 2018 and no longer accepts applications; a taxpayer whose conduct was willful should instead look at the IRS Criminal Investigation Voluntary Disclosure Practice.
Either way, the underlying throwback tax and §668 interest charge still apply.
Throwback tax vs. PFIC rules: overlapping traps for foreign trust investors
A foreign trust holding mutual funds or foreign ETFs is almost certainly holding PFICs, meaning a single distribution to a US beneficiary could simultaneously trigger both PFIC excess distribution tax and throwback tax.
This overlap creates one of the most punitive tax scenarios in the Internal Revenue Code.
How both layers of tax stack up
- PFIC layer: Under IRC §1291, excess distributions from a PFIC are taxed at the highest marginal rate for the year – 37% for 2025, and unchanged going into 2026 – plus an interest charge. Form 8621 is required.
- Throwback layer: If those PFIC gains accumulate inside a non-grantor foreign trust, a subsequent distribution to a US beneficiary triggers throwback tax under §§665–668, with its own §668 interest charge. Form 3520 is required.
The result is a potential double layer of punitive taxation on the same distribution – each with its own interest charge computed independently.
Planning around this overlap requires coordination between PFIC analysis and trust distribution planning.
In many cases, ensuring the trust makes annual distributions – or converting to grantor trust status – can mitigate both layers of tax.
See our guide on green card holders and foreign income for more on how US tax obligations interact with foreign investment income.
Frequently asked questions
The throwback tax is a federal tax that applies when a trust distributes income it accumulated in prior years.
Instead of taxing the distribution at current-year rates, the IRS computes the tax as if the beneficiary had received the income in the years it was earned, using the beneficiary's historical tax rates under IRC §667.
For foreign trusts, an additional interest charge applies under §668.
For most domestic trusts created after March 1, 1984, no. The Taxpayer Relief Act of 1997 effectively repealed the federal throwback rules for domestic trusts by treating them as “qualified trusts” under IRC §665(c).
The rules still apply to domestic trusts created before that date and to trusts that were once classified as foreign.
The interest charge applies only to foreign trust distributions. It uses the IRC §6621 underpayment rate – with daily compounding for accumulation years after 1995 – applied to each year's share of the throwback tax.
The charge is not deductible, and combined with the tax, it cannot exceed the total accumulation distribution.
Likely yes, if your interest in the trust is contingent and the trust paid no tax on the accumulated income. That is the R&TC §17745(b) scenario, and the tax is computed under §17745(d).
That computation includes the income ratably over the distribution year and the five preceding tax years, or over the period the trust accumulated income for you as a contingent beneficiary, whichever is shorter. It isn't limited to the years you lived in California, so don't assume income accumulated before your move is automatically excluded.
California tax rates for trusts reach up to 13.3% (2025). If the trust issued you a Schedule J (541), FTB Form 5870A directs you to the federal IRC §667 averaging method instead of the §17745 computation.
These are sales apportionment rules, not trust rules. The throwback rule assigns a sale back to the seller's home state when the buyer's state does not tax the seller. The throwout rule removes that sale from the denominator entirely.
Both increase the seller's in-state tax, but through different mechanisms.
Generally, no – refusing or disclaiming a distribution does not retroactively eliminate the trust's accumulated UNI.
The throwback rules remain in effect for any future distribution from that trust. The most effective approach is proactive planning: ensuring the trust distributes income annually so UNI does not accumulate.
A distribution from a foreign trust includes any transfer of property or payment of money from the trust to a US beneficiary. Under IRC §643(i), it also includes loans of cash or marketable securities from the trust and uncompensated use of other trust property. Each is treated as a distribution even though no transfer of ownership occurs.
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