Blog Country Specific Expat Tax Situations

UK Pension Reporting for Americans: SIPPs and U.S. Tax Rules

If you are a U.S. citizen with a UK pension, such as a Self-Invested Personal Pension (SIPP) or a workplace scheme, you must report it to the IRS every year, even though it is a UK retirement account, because the U.S. taxes its citizens on worldwide income and assets. Reporting a UK pension on your U.S. tax return means putting the account on an FBAR and often Form 8938, deciding how to treat the growth inside it under the U.S.-UK tax treaty, and knowing that the UK’s 25% tax-free lump sum may still be taxable in the U.S. The treaty and IRS rules on foreign pension distributions shape how U.S. tax on a UK pension is applied in practice.

Here is what a SIPP means for your U.S. return:

Reporting first: a SIPP is a foreign financial account, so it usually goes on your FBAR and may go on Form 8938.
No U.S. deduction: your SIPP contributions are not deductible on your U.S. return, the way they reduce your UK tax.
Treaty positions matter: the U.S.-UK treaty can defer U.S. tax on growth within the SIPP, but you must claim that position actively.
The lump sum is contested: the UK’s 25% tax-free lump sum is not automatically tax-free for U.S. purposes.

Your UK Pension, Reported Right on Both Sides

A UK pension is one of the easiest accounts to misreport and one of the costliest. Greenback files your UK and U.S. returns together so the treaty positions and FBAR line up.

This article walks through what a SIPP is, how the U.S. treats contributions and growth, the FBAR and FATCA forms, what the treaty says, how withdrawals and lump-sum distributions are taxed, and the mistakes that cost expats the most.

A SIPP Is a UK Personal Pension With Distinct U.S. Tax Rules

A Self-Invested Personal Pension is a UK defined-contribution pension that you fund and control, choosing the investments inside it rather than leaving them to a workplace scheme. SIPPs are common among Americans living in the UK, especially the self-employed and anyone consolidating old workplace pensions, because they offer flexibility and UK tax relief on contributions. The U.S. reporting approach in this guide applies to most UK private and workplace pensions, with the SIPP as the leading example because it is the one Americans hold most often.

That UK tax relief is exactly where the U.S. complication begins. The UK treats a SIPP as a tax-favored pension: contributions reduce your UK tax, and the growth inside is free of UK tax until you draw on it. The U.S. does not automatically mirror any of that. To the IRS, a SIPP is a foreign account holding foreign investments, and the default U.S. rules can be far less generous than the UK ones unless the tax treaty steps in. Getting the reporting right protects you from penalties that often dwarf the tax involved. For how a SIPP fits the wider UK filing picture, see our U.S. expat tax guide for living in the UK, and for the baseline rules on any overseas pension, our guide to how foreign pensions are taxed.

A SIPP is a private pension and is treated differently from the UK State Pension, which has its own treaty treatment. This article covers SIPPs and other private UK pensions; if you are moving a pension between schemes, that is a separate question covered by QROPS transfer rules.

Here is the reassuring part to hold onto as you read. For most U.S. citizens in the UK, a SIPP creates reporting work rather than a real U.S. tax bill, because the Foreign Tax Credit usually offsets U.S. tax on any pension income the UK has already taxed. The expensive mistakes with a SIPP are almost always missed forms, not the tax itself, which is exactly why knowing the rules ahead of time pays off.

How the U.S. Taxes SIPP Contributions and Growth

Here is the SIPP lifecycle at a glance, with the details in the sections that follow:

Stage	UK treatment	U.S. treatment
Contributions	Tax relief reduces your UK tax	No deduction on your U.S. return
Growth inside the SIPP	Tax-free until you withdraw	Often deferred under the treaty, claimed on Form 8833
25% lump sum	Tax-free up to £268,275	May be taxable; default or treaty position
Regular withdrawals	Taxed as income	Reported on your U.S. return, with the Foreign Tax Credit offsetting UK tax

Two questions drive the U.S. treatment during the years you are building the SIPP: are contributions deductible, and is the internal growth taxed as it accrues?

Contributions are generally not deductible on your U.S. return. The UK gives you tax relief on what you pay into a SIPP, but that relief does not carry over to your Form 1040. For a personal SIPP, U.S. law provides no matching deduction, so contributions are made with income that remains fully subject to U.S. tax.
Growth inside the SIPP can often be deferred under the treaty, but that is a position you claim. Without treaty protection, the IRS could try to tax dividends, interest, and gains accumulating in the account each year. Article 18 of the U.S.-UK tax treaty allows many U.S. taxpayers to defer U.S. tax on that internal growth until distributions are taken, matching the UK timing. Because this is a treaty position rather than an automatic rule, it is typically claimed on Form 8833, and whether it applies to your specific SIPP is a question for a professional.

One trap sits inside the investments. A SIPP frequently holds UK-domiciled funds, and the IRS may classify them as passive foreign investment companies (PFICs), which are subject to punitive tax and Form 8621 reporting. There is a reasonable argument that assets held inside a treaty-qualified pension are sheltered from the PFIC regime, but the analysis is fact-specific. Check the PFIC status of your holdings before assuming you are protected. Our guide to PFIC tax rules explains the stakes.

FBAR and FATCA Reporting for a SIPP

A SIPP is a foreign financial account, so the reporting obligations are usually the most immediate part of owning one. Skipping them is where the largest penalties arise, often regardless of whether any tax is due. The two that almost always apply are the FBAR and, once your foreign assets cross the thresholds, Form 8938.

Form	When it applies to a SIPP	Threshold
FBAR (FinCEN Form 114)	Almost always, once total foreign accounts are large enough	Over $10,000 combined across all foreign accounts at any point in the year
Form 8938 (FATCA)	When foreign financial assets exceed the threshold	$200,000 (single, abroad, year-end) or higher; $400,000 if married filing jointly abroad
Form 8621 (PFIC)	If the SIPP holds funds the IRS treats as PFICs and no pension exception applies	No de minimis once reportable
Forms 3520 / 3520-A	Foreign trust reporting, unless the SIPP qualifies for relief	See below

The trickiest of these is the foreign trust question. The IRS treats some foreign pensions as foreign trusts that would otherwise require Forms 3520 and 3520-A. Revenue Procedure 2020-17 created an exemption for certain tax-favored foreign retirement trusts, and many practitioners believe a SIPP can qualify, thereby removing the 3520 and 3520-A burden. The relief is not automatic: it depends on the specific plan meeting the revenue procedure’s conditions, and it is available only to taxpayers who are otherwise compliant on the income side. Even when it applies, it removes only the 3520 and 3520-A forms. Your FBAR, Form 8938, any PFIC reporting, and U.S. tax on income are unaffected.

What the U.S.-UK Tax Treaty Says About Pension Income

The U.S.-UK tax treaty is what keeps a SIPP from being taxed harshly and twice. Its pension provisions (Articles 17 and 18) generally assign taxing rights on pension income to the country where you live, so a UK resident’s SIPP income is primarily a UK matter.

For a U.S. citizen, though, the treaty’s saving clause is the catch. As the IRS explains, the saving clause allows the U.S. to continue taxing its citizens as if the treaty did not exist, except where a specific paragraph is carved out of it. In plain terms, you usually still report SIPP income on your U.S. return, then use the Foreign Tax Credit for the UK tax you paid, so the same money is not taxed twice. The treaty sets the framework; the Foreign Tax Credit does the heavy lifting on your 1040.

For how the treaty’s saving clause and key articles work, see our explainer on the U.S.-UK tax treaty.

How SIPP Withdrawals Are Taxed, Including the 25% Lump Sum

When you start drawing on the SIPP, the U.S. treatment splits between regular pension payments and the headline 25% lump sum.

Regular pension payments are reported as income on your U.S. return. If you are a UK resident, the UK taxes them too, and you claim the Foreign Tax Credit for the UK tax to offset your U.S. liability. The taxable amount for U.S. purposes is generally the distribution minus your cost (your own previously taxed contributions).

The 25% tax-free lump sum is where U.S. and UK treatment diverges, and where professionals genuinely disagree. The UK lets you take up to 25% of your pension as a tax-free Pension Commencement Lump Sum, capped by the Lump Sum Allowance of £268,275. The UK treating it as tax-free does not make it tax-free in the U.S.

There are two paths:

Path	What you do	The trade-off
Default path	Report the lump sum as U.S.-taxable income	Conservative and simple, but you may owe U.S. tax with no UK tax to credit against it
Treaty-position path	Claim under Article 17(1)(b) that the lump sum is taxable only in the UK, filing Form 8833	Potentially no U.S. tax, but the position is unsettled with the IRS and could be challenged

Which path fits depends on your facts and your appetite for a contestable position.

Consider Priya, a U.S. citizen living in Bristol with a £400,000 SIPP. She takes her 25% lump sum of £100,000 (about $125,000). The UK charges no tax on it. On the default path, she reports $125,000 on her U.S. return and owes U.S. tax because there is no UK tax to offset it. On the treaty-position path, she files Form 8833 to claim the lump sum is UK-only and excludes it, accepting that the position could be challenged. The difference can run into tens of thousands of dollars, which is why the choice is worth professional analysis.

Common SIPP Reporting Mistakes and How to Avoid Them

Assuming UK tax-free means U.S. tax-free. The 25% lump-sum and the SIPP’s internal growth are tax-favored in the UK, but not automatically in the U.S.
Missing the FBAR or Form 8938. A SIPP is a reportable foreign account, and the penalties for omitting it are steep even when no tax is owed.
Ignoring PFICs inside the SIPP. UK funds held in the account can trigger Form 8621 and punitive tax if no pension exception applies.
Skipping Form 8833 for treaty positions. Deferring tax on growth or excluding the lump sum are positions you must claim, not defaults.
Assuming Forms 3520 and 3520-A always, or never, apply. Whether Rev. Proc. 2020-17 relief covers your SIPP is a case-by-case call.
Filing late and unprotected. If you are behind, the Streamlined Filing Procedures often let you catch up with little or no penalty.

A Practical Checklist for Your SIPP at U.S. Tax Time

Use this as a starting point each year, and bring anything you are unsure about to a professional:

Report the SIPP on your FBAR if your foreign accounts total $10,000 or more at any point in the year.
Add Form 8938 if your total foreign financial assets cross the FATCA threshold.
Check whether any funds inside the SIPP are PFICs, and confirm whether the pension exception applies before assuming you are in the clear.
Decide whether to defer U.S. tax on the SIPP’s growth under the treaty, and file Form 8833 if you take that position.
Confirm whether your SIPP qualifies for Revenue Procedure 2020-17 relief from Forms 3520 and 3520-A.
When you take money out, report distributions on your U.S. return and claim the Foreign Tax Credit for the UK tax you paid.
Treat the 25% lump sum as a planning decision, not an afterthought, and choose the default or treaty path deliberately.
If you are behind on any of this, look at the Streamlined Filing Procedures to catch up before the IRS contacts you.

How Greenback Helps Americans With UK and U.S. Taxes

A SIPP sits in the hardest corner of expat tax: a UK account with UK tax rules that the U.S. only partly respects, plus contested treaty positions and overlapping forms. Greenback handles both your UK and U.S. returns on a single account, with a UK Chartered Accountant and a U.S. CPA on the same file, so your SIPP is reported consistently on both sides, and the treaty positions are applied with eyes open.

If you are a U.S. citizen with a UK pension, we make sure the reporting is right and the strategy is sound. Learn more about how we help Americans living in the UK.

One Team for HMRC and the IRS

One team, one account, both returns. We make sure your UK pension is reported correctly to the IRS and HMRC so retirement planning is the only thing on your mind, not a filing surprise.

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Frequently Asked Questions about UK Pension Reporting

Do I have to report my UK SIPP to the IRS?

Yes. A SIPP is a foreign financial account, so it generally goes on your FBAR once your foreign accounts exceed $10,000 combined, and on Form 8938 if you cross the FATCA thresholds. Reporting is required even in years when no tax is due.

Is the growth in my SIPP taxed in the U.S. each year?

Often it can be deferred. Article 18 of the U.S.-UK tax treaty allows many U.S. taxpayers to defer U.S. tax on the SIPP’s internal growth until distribution, but this is a treaty position you claim, typically on Form 8833, rather than an automatic rule.

Is the UK 25% tax-free lump sum taxable in the U.S.?

It may be. The UK treats up to 25% as tax-free, capped at the £268,275 Lump Sum Allowance, but the U.S. does not automatically follow suit. Most firms treat it as U.S.-taxable on the default path, while some claim a treaty exemption under Article 17(1)(b) on Form 8833. The position is unsettled, so get professional advice.

Do I need to file Form 3520 for a SIPP?

Maybe not. Revenue Procedure 2020-17 exempts certain tax-favored foreign retirement trusts from Forms 3520 and 3520-A, and a SIPP can qualify if it meets the conditions and you are otherwise compliant. The relief does not remove FBAR, Form 8938, PFIC, or income tax obligations.

Can I deduct my SIPP contributions on my U.S. tax return?

No. UK tax relief on SIPP contributions does not carry over to your U.S. return, so for a personal SIPP, the contributions are made from income that remains subject to U.S. tax.

What happens to my SIPP if I move back to the U.S.?

You keep reporting it, and U.S. tax on distributions follows the same treaty framework, though your residency change affects where the income is primarily taxed. Because the analysis shifts when you become a U.S. resident again, review it with a professional before you draw on the pension.

This article is for informational purposes only and does not constitute tax, legal, or financial advice. U.S. and UK tax laws and treaty interpretations change; several positions described here are unsettled, and your situation is unique. Always confirm current rules with official IRS and HMRC sources and consult a qualified professional before making decisions about your pension.