Introduction: Why a BBA Partnership Audit Reaches Partners Living in Britain
A BBA partnership audit is an IRS examination of a US partnership under the centralised regime created by the Bipartisan Budget Act of 2015, in which the IRS assesses and collects any extra tax from the partnership itself rather than from each partner. If you live in London and hold an interest in a US private equity fund, a real estate limited partnership or a family LLC, that regime decides who pays for mistakes made years ago, and at what rate.
Most Americans in Britain only discover the BBA partnership audit rules when a fund administrator emails a notice about a push-out election or a reduced distribution. By then, the key deadlines are usually running. Furthermore, the regime was designed around domestic US investors, so it says nothing about HMRC, the US-UK treaty or your own UK Self Assessment return. As a result, a UK-resident partner can end up paying American tax twice over in economic terms, once through the fund and once without any matching UK relief.
At TaxYork, we prepare US and UK returns for investment bankers, fund principals and business owners whose wealth sits partly inside US partnerships. This guide explains how a BBA partnership audit works in 2026, where the cross-border traps lie, and what you can do at each stage to protect your position on both sides of the Atlantic.
BBA Partnership Audit in One Paragraph
The regime applies to partnership returns for tax years beginning on or after 1 January 2018, and it replaced the older TEFRA procedures. Under the IRS centralised partnership audit regime, the IRS examines the partnership, deals only with a single partnership representative, and calculates an imputed underpayment at the partnership level. Partners have no statutory right to take part in the examination. Instead, the partnership chooses whether to pay that bill itself, reduce it through modification, or push the adjustments out to the people who were partners in the year under review.
Who This Guide Is Written For
We wrote this guide for US citizens and green card holders resident in the UK, for dual national US UK investors, and for British investors whose US fund interests make them partners in an American entity. In particular, it addresses limited partners in US funds, members of US LLCs taxed as partnerships, and founders who hold carried interest through a US vehicle. If a K-1 arrives in your post each spring, a BBA partnership audit of that entity can reach you, wherever you live. Many of these investors hold interests through a limited partnership and have never read the audit clauses in its agreement.
How the BBA Partnership Audit Process Works in 2026
Every BBA partnership audit follows the same broad sequence, and understanding it matters because your options narrow at each step. The IRS describes the BBA partnership audit process as a field examination followed by a notice of proposed partnership adjustment, an optional modification phase, a final partnership adjustment and an optional push-out phase.
The Partnership Representative Controls Everything
In every BBA partnership audit, the partnership must have a named partnership representative, and that person or entity binds every partner. Specifically, the representative alone negotiates with the IRS, agrees settlements and decides whether to request modification or make a push-out election. You can read the IRS rules on designating a partnership representative to see how wide that authority is. Consequently, your protection depends on the partnership agreement, not on the statute. We recommend that every UK-resident investor checks whether the fund documents oblige the representative to consult partners, to consider foreign partners, and to share audit notices promptly.
The Imputed Underpayment and the 37% Rate
When a BBA partnership audit finds that income was understated, the IRS nets the adjustments and multiplies the result by the highest individual or corporate rate in force for the reviewed year. For individuals, that rate is 37%, which the One Big Beautiful Bill Act made permanent from 2026. The IRS explains the arithmetic in its guide on how to figure an imputed underpayment. Importantly, the partnership pays the bill in the adjustment year, so the cost falls on whoever owns the partnership when the audit closes. Therefore, a partner who joined after the reviewed year can bear part of an old liability, while a partner who has since sold out may escape it entirely.
The Timetable You Must Watch
After the notice of proposed partnership adjustment in a BBA partnership audit, the partnership has 270 days to request modification. Once the final partnership adjustment is issued, the representative has 45 days to file Form 8988 and elect to push out. If the audit becomes final and the election stands, the partnership then has 60 days to file Forms 8985 and 8986 and to furnish each Form 8986 to the reviewed-year partners. Moreover, that 60-day deadline cannot be extended. Missing it invalidates the push-out, and the partnership then owes the full imputed underpayment.
Modification: Cutting the Imputed Underpayment for UK-Resident Partners
Modification is the stage of a BBA partnership audit where foreign and UK-resident partners have the most to gain, and it is also the stage most fund managers overlook. The modification rules in Treasury Regulation 301.6225-2 allow the partnership to replace the flat 37% calculation with figures that reflect the partners' real tax positions.
Amended Returns and the Pull-In Procedure
The first route lets reviewed-year partners take their share of the adjustments onto their own returns and pay the tax themselves. In practice, most partners now use the alternative pull-in procedure, which avoids filing a full amended return for every year affected. However, a UK-resident American can only use this route cleanly if their own US filings are in order. If you have missed US tax returns or a missed FBAR for the same years, the pull-in will expose those gaps. In our experience, that is the moment to bring your personal compliance up to date first, often alongside a review of your FBAR and FATCA reporting.
Rate Modification for Capital Gains and Dividends
The second route substitutes a lower rate where the adjustment relates to long-term capital gains or qualified dividends allocated to individuals. For example, an adjustment to the gain on a property sale might qualify for the 20% rate instead of 37%. Similarly, corporate partners can request the 21% corporate rate. For real estate and private equity funds, where most profit is capital in nature, this BBA partnership audit modification alone can reduce the bill by almost half.
The Treaty Modification Most Funds Never Request
The third route matters most to readers of this guide. Regulation 301.6225-2(d)(9) allows modification where a reviewed-year partner was entitled to a reduced rate or exemption under an income tax treaty. Therefore, a British investor who is not a US person, and whose share of the adjusted income would have been exempt or taxed at a reduced treaty rate under the US-UK double taxation convention, can ask the partnership to remove or reduce that share of the imputed underpayment. Notably, this route does not usually help a US citizen living in the UK, because the treaty's saving clause preserves the US right to tax its own citizens. Nevertheless, it can help a non-US spouse who holds a fund interest directly.
The Push-Out Election and Form 8986 for Partners Abroad
The push-out election under Internal Revenue Code section 6226 transfers responsibility for the tax from the partnership to the people who were partners in the reviewed year. For a UK-resident partner, a push-out is often the better outcome, but it carries its own costs.
What Form 8986 Tells You
Form 8986 sets out your share of each adjustment, the reviewed year concerned, and the date by which a pass-through partner must either push the adjustment further or pay. You do not amend your earlier returns. Instead, you calculate the extra tax that would have arisen in the reviewed year and each intervening year, and you add that amount to your US return for the year in which the partnership furnished the statement, using Form 8978. Consequently, an adjustment to 2023 can land on your 2026 Form 1040, due while you are also preparing your 2026-27 UK return.
The Higher Interest Charge
A push-out after a BBA partnership audit is not free. Interest on the pushed-out tax runs from the original due date of the reviewed-year return at two percentage points above the normal underpayment rate. Additionally, any penalties are determined at the partnership level and pass through with the adjustment. Therefore, the longer an audit runs, the more the push-out interest erodes its advantage over the imputed underpayment.
Why the Push-Out Usually Favours UK Residents
Despite the higher interest, a push-out following a BBA partnership audit puts the tax on your own return, in your own name, computed on your own income. That matters for HMRC, as the next section explains. Furthermore, it means the cost follows the person who received the income, so you do not subsidise new investors or bear a share of tax on income you never received. For non-US partners, a push-out may also require a Form 1040-NR, so the partnership should flag this before it elects.
Claiming UK Credit After a BBA Partnership Audit
This is the gap that no other guide on the subject covers, and it is where most of the money is lost. A BBA partnership audit changes your US tax on income that HMRC may already have taxed in full. Whether you recover any of the extra US tax in the UK depends on how the tax was paid and how quickly you act.
Why Entity-Level Tax Is Hard to Credit
UK foreign tax credit relief requires foreign tax that is computed by reference to the same income on which you pay UK tax, and that you can show was borne on your income. Under the default regime, the imputed underpayment is legally the partnership's liability, calculated at a flat rate on net adjustments, and paid in a later year by a different group of owners. As a result, a UK-resident partner may struggle to evidence that any identifiable part of it was tax on their own share of income. In our experience, HMRC expects a clear link between the foreign tax and the claimant, and a partnership-level payment rarely supplies it without careful documentation from the fund.
The Time Limits for a UK Claim
For income tax, a claim for credit relief must normally be made within four years of the end of the tax year concerned or, if later, by 31 January following the tax year in which the foreign tax is paid. HMRC sets out these time limits for double taxation relief claims. Additionally, where credit has already been allowed and a later foreign adjustment changes the tax payable, an extended six-year window runs from the date of the adjustment. A push-out, paid in the reporting year, fits these rules far more naturally than an entity-level payment. You can read more about the HMRC side in our guide on foreign tax redetermination when a tax bill changes.
Matching the Character of the Income
Even with a push-out, the UK credit after a BBA partnership audit only works if the income is the same income in both countries. For instance, the UK may tax a US fund's rental profit with no deduction for American depreciation, while the IRS adjustment may concern the depreciation itself. In that case, the UK tax already exceeded the US tax, and the US increase often becomes fully creditable. By contrast, where the adjustment changes a gain into ordinary income, the UK classification may not move at all. Careful matching of the Schedule K-1 and the Schedule K-3 figures against your UK computation is therefore essential, and our tax treaty optimisation service exists precisely for that reconciliation.
Electing Out and Correcting Errors Before the IRS Arrives
The best way to handle a BBA partnership audit is often to avoid the centralised regime altogether, or to correct errors before the IRS finds them. Both routes are open to many family and closely held partnerships with UK-resident partners.
Electing Out for Small Partnerships
A partnership with 100 or fewer partners can elect out of the regime each year on its timely filed Form 1065, provided every partner is an eligible partner. Under the IRS election-out rules, eligible partners include individuals, C corporations, S corporations, estates of deceased partners and foreign entities that would be C corporations if domestic. Notably, a UK private limited company usually counts as a foreign corporation by default, so it does not break the election. However, a UK LLP, another partnership or a disregarded entity does. If you hold a family LLC interest through a UK LLP, restructuring the holding may restore the election out and return any future audit to individual partners.
Administrative Adjustment Requests
When a partnership spots its own error after filing, it cannot simply issue amended K-1s, and an uncorrected error is exactly what a later BBA partnership audit will find. Instead, it files an administrative adjustment request, and the partners take the corrections into account in the year the request is filed. The IRS guidance on filing an AAR explains the mechanics, which run through Form 8082 for paper filers. Importantly, an AAR filed before the IRS opens an examination usually avoids the higher push-out interest and gives you a cleaner trail for any UK credit claim.
The Statute of Limitations
The IRS generally has three years from the later of the filing date, the due date or the AAR date to issue a notice of proposed adjustment, under Internal Revenue Code section 6235. That window extends by 270 days, plus any agreed extensions, once modification begins. Consequently, a BBA partnership audit of a 2023 partnership return can still produce a Form 8986 in late 2026 or 2027, long after you have filed both your US and UK returns for that year.
Case Study: A London Banker in a US Real Estate Fund
The following illustrative example shows how the same BBA partnership audit can produce very different results depending on the choices the partnership representative makes.
The Background
Claire is a US citizen and managing director at a London investment bank, resident in the UK since 2018. She holds a 2.5% limited partnership interest in a US multifamily real estate fund. In 2026, the IRS completes a BBA partnership audit of the fund's 2023 return and disallows $40 million of cost segregation deductions, which increases the fund's 2023 ordinary rental income by the same amount.
The Default Result
Without modification or a push-out, the imputed underpayment is $40 million at 37%, or $14.8 million, paid by the fund in 2026. Claire's economic share at 2.5% is $370,000, taken from her capital account. However, she has no personal US tax payment to show HMRC, and the fund's investor letter describes the cost as a partnership expense. Moreover, a pension fund that bought an interest in 2025 bears part of the bill, while an investor who sold in 2024 bears none. Claire's position is therefore that she has borne $370,000 of US tax that she cannot credit against the UK tax she already paid on the same rental profits.
The Push-Out Result
Instead, Claire's advisers persuade the partnership representative to elect a push-out. She receives a Form 8986 showing $1 million of additional 2023 ordinary income. At her 37% marginal rate, her additional reporting-year tax is $370,000, plus roughly $95,000 of interest at the higher push-out rate, which she reports on Form 8978 with her 2026 Form 1040. Because HMRC had taxed her share of the fund's 2023 rental profit at 45% without any US depreciation deduction, the extra US tax relates to income that the UK already taxed more heavily. She therefore lodges a UK credit claim within the time limits and recovers about £290,000 of UK tax, at an assumed exchange rate of 1.27. Her net cost falls from $370,000 with no relief to the interest charge and professional fees. Additionally, we check her FBAR filings with FinCEN and her Form 8938 history for 2023 before the Form 8986 reaches her return, so no missed reporting surfaces at the same time.
How TaxYork Can Help
We provide comprehensive US and UK tax return preparation for partners in US funds who live in Britain. When a BBA partnership audit notice arrives, we review the fund's proposed adjustments, model the default, modification and push-out outcomes, and prepare the information your fund needs to request a treaty or rate modification. Furthermore, we prepare Form 8978 and the related US return, reconcile the K-1 and K-3 figures against your UK computation, and file the matching HMRC credit claim within the correct window. Where earlier years show missed US tax returns or missed FBAR filings, we bring those up to date first so the audit does not open a second front. You can also explore our wider cross-border planning service for fund structuring questions.
Conclusion
A BBA partnership audit is decided by the partnership representative, timed by deadlines you do not control, and priced at 37% unless someone acts. For UK-resident partners, the default BBA partnership audit outcome, an entity-level imputed underpayment, is usually the worst result, because it leaves you bearing American tax that HMRC may never credit. In contrast, a push-out, a treaty or rate modification, or an early AAR can align the US tax with your own income and keep the UK relief alive. Therefore, read every fund audit notice the day it arrives, check your partnership agreement now, and make sure your own US and UK filings are complete before any adjustment reaches your return.
Contact Us
If your US fund or family LLC has received an audit notice, or you want your position reviewed before one arrives, book a consultation with our US-UK team. Email hello@taxyork.com or call 020 3488 8606. We act quickly when the 45-day and 60-day windows are already running.
Disclaimer
This article provides general information about US and UK tax rules as at October 2026 and does not constitute tax, legal or financial advice. The case study is illustrative and uses simplified figures and an assumed exchange rate. Tax outcomes depend on your individual circumstances, your partnership agreement and the law in force at the relevant time. You should obtain professional advice before acting on any matter discussed here. TaxYork accepts no liability for actions taken in reliance on this article.