Introduction: The Innovative Finance ISA Problem for US Citizens
An Innovative Finance ISA pays you peer-to-peer interest that Britain never taxes, yet the IRS taxes every penny of it as ordinary income. That single mismatch catches thousands of American bankers, lawyers and company owners in London each year. Moreover, the product itself changed on 6 April 2026, and a further round of ISA reform arrives in April 2027. Consequently, most of the guidance you will find online is already out of date.
At TaxYork, we prepare US and UK returns for high-net-worth Americans who hold peer-to-peer loan books, crowdfunding bonds and, since this spring, crypto exchange traded notes inside their ISA. In our experience, the Innovative Finance ISA is the ISA that US filers most often leave off their returns entirely. It feels like a savings product. However, the IRS sees a foreign lending portfolio, a foreign financial account and, in some cases, a foreign currency position that moves every time a loan repays.
This guide therefore covers everything the ranking pages skip. You will see how the IRS taxes Innovative Finance ISA interest, why the arithmetic still favours the wrapper for an additional-rate American, what happens when a borrower defaults, how currency gains arise on sterling loans, and exactly what the 2026 and 2027 rule changes mean for you. Finally, we walk through a full case study with real numbers.
What an Innovative Finance ISA Holds in 2026
An Innovative Finance ISA is the third type of adult ISA, introduced on 6 April 2016 to let UK residents lend money tax-free through regulated platforms. According to HMRC guidance on Innovative Finance ISA investments, the wrapper can hold peer-to-peer loans, crowdfunding debentures, certain less-liquid property investments, alternative finance arrangements and sterling cash on deposit.
Importantly, the menu changed this year. The Individual Savings Account (Amendment) Regulations 2026 moved Long Term Asset Funds out of the Innovative Finance ISA and into the stocks and shares ISA from 6 April 2026. At the same time, cryptoasset exchange traded notes became eligible for the Innovative Finance ISA only. As a result, the wrapper now holds a mix of assets that the IRS treats in at least four different ways.
Furthermore, the overall ISA subscription limit remains £20,000 per tax year. You can split that allowance across cash, stocks and shares, innovative finance and Lifetime ISAs, and you can now open more than one Innovative Finance ISA in the same year.
Why the IRS Ignores the ISA Wrapper
The ISA exemption exists only in UK law. The US-UK tax treaty contains no article that exempts ISA income, and the saving clause preserves the right of the United States to tax its citizens as if the treaty did not exist. Therefore, the IRS looks straight through the wrapper to the loans underneath.
In practice, this means your IFISA is simply a taxable account for US purposes. Every interest payment, every default and every currency movement produces a US tax consequence. Additionally, because the platform is a UK financial institution, the account can trigger FBAR and Form 8938 reporting. Neither the platform nor HMRC will warn you, and no UK platform issues a Form 1099.
How the IRS Taxes Innovative Finance ISA Interest
Peer-to-peer interest is ordinary income to the IRS. You report it on Schedule B and it is taxed at your marginal federal rate, which reaches 37% for high earners. Moreover, the income has no special character that could lower the rate, because interest never qualifies for the preferential rates that apply to qualified dividends and long-term capital gains.
Timing and Source of the Interest
As a cash-basis individual, you are generally taxed on interest when it is paid or credited to your ISA cash balance. Reinvesting it automatically into new loans does not defer the charge. Similarly, interest that the platform credits and then holds as uninvested cash is still income in that year.
Under section 861 of the Internal Revenue Code, interest is sourced by the residence of the borrower. Loans to UK individuals and UK companies therefore produce foreign-source income. That matters for the foreign tax credit limitation, as we explain below. Notably, peer-to-peer interest falls in the passive category basket on Form 1116, not the general basket that holds your salary.
The Net Investment Income Tax Adds 3.8%
High earners also face the Net Investment Income Tax. The 3.8% charge applies to interest once your modified adjusted gross income exceeds $200,000 single or $250,000 married filing jointly. Those thresholds are not indexed. Consequently, almost every senior City professional pays it.
Crucially, the foreign earned income exclusion is added back when you calculate the NIIT threshold. On 31 August 2026 the Federal Circuit also held, in two companion precedential decisions, that no treaty foreign tax credit can reduce the NIIT. As a result, the top federal charge on Innovative Finance ISA interest is 40.8%, and nothing British can offset the final 3.8%.
Why the Foreign Earned Income Exclusion Cannot Help
The foreign earned income exclusion shelters up to $132,900 of 2026 wages. However, it covers earned income only. Peer-to-peer interest is unearned investment income, so the exclusion never reaches it. Instead, your only possible relief is the foreign tax credit, and inside the wrapper there is no UK tax to credit.
Translating Sterling Interest Into Dollars
You must report the income in US dollars. For recurring income received through the year, most filers use the IRS yearly average exchange rate, which was 0.759 pounds per dollar for 2025. Alternatively, you can translate each payment at the spot rate on the day it arrives. Whichever method you choose, apply it consistently across years. Our guide to which exchange rate to use on US and UK returns explains the choice in detail.
The Innovative Finance ISA Arithmetic for an Additional-Rate American
Most American expat guides tell you to avoid every ISA. For stocks and shares ISAs holding UK funds, that advice is usually right, because of the PFIC rules. For an Innovative Finance ISA holding plain loans, however, the answer is different. The numbers often favour keeping the wrapper.
A Taxable Peer-to-Peer Account Costs More
Outside the ISA, an additional-rate taxpayer pays 45% UK income tax on peer-to-peer interest, with no personal savings allowance at that level. Because 45% exceeds the top US rate of 37%, the high-tax kickout moves that interest from the passive basket into the general basket. The UK tax then fully covers the regular US tax, but the NIIT of 3.8% still falls due. Your total burden is therefore about 48.8%.
Furthermore, the excess UK credit rarely helps you. A London banker already has surplus general-basket credits from UK salary taxed at 45%. So the extra credit simply joins a carryforward that expires unused after ten years.
Inside the Wrapper the Burden Falls
Inside an Innovative Finance ISA, by contrast, Britain charges nothing. You pay the US tax of 37% plus the 3.8% NIIT, a total of 40.8%. In other words, the wrapper saves you roughly eight percentage points on every pound of interest. This is the opposite of the conventional wisdom, and it is the single most valuable point in this guide.
The Gap Widens From April 2027
The saving grows next year. From 6 April 2027 the UK introduces separate savings income rates of 22%, 42% and 47%. A taxable peer-to-peer account held by an additional-rate American will then suffer 47% UK tax, while the Innovative Finance ISA still suffers none. Accordingly, filling your £20,000 allowance each year becomes more valuable, not less, provided you stay away from assets that create PFIC problems.
Where the Wrapper Loses Its Edge
The advantage depends on your UK marginal rate. A non-working American spouse, for example, may have almost no other UK income. In that case the personal allowance of £12,570, the £5,000 starting rate for savings and the £1,000 personal savings allowance can shelter up to £18,570 of interest in a taxable account anyway. Consequently, the wrapper saves that spouse nothing in Britain, while the US tax is identical in both places.
Similarly, a basic-rate taxpayer pays only 20% UK tax outside the ISA, rising to 22% from April 2027. That tax is creditable against the US charge on the same interest. So the real saving shrinks to the gap between the UK rate and the top US rate, which is often zero. In short, the wrapper earns its keep mainly for additional-rate and higher-rate Americans, and it should never absorb allowance that a better-suited holding could use.
When Loans Default: Bad Debt Relief on Both Sides of the Atlantic
Defaults are a normal part of peer-to-peer lending, and money in an Innovative Finance ISA is not protected by the Financial Services Compensation Scheme if a borrower fails. The two tax systems then treat the loss in completely different ways.
The UK Relief You Give Up Inside the ISA
Outside an ISA, section 412A of the Income Tax Act 2007 gives relief for irrecoverable peer-to-peer loans. You set the lost principal against your peer-to-peer interest, and any unused loss can be carried forward. HMRC explained the design when it launched the wrapper in its note on the Innovative Finance ISA and peer-to-peer loans.
Inside an Innovative Finance ISA, however, no UK relief exists, because the income was never taxable. In the UK, the loss simply reduces the value of your ISA.
The US Treats a Default as a Capital Loss
The IRS, by contrast, still allows a loss. A peer-to-peer loan made as an investment is usually a nonbusiness debt under section 166 of the Internal Revenue Code. When it becomes wholly worthless, you claim a short-term capital loss in that year. Notably, no deduction is available for partial worthlessness, so a loan that the platform is still pursuing generally cannot be written off yet.
That capital loss first offsets your capital gains. After that, only $3,000 a year can reduce ordinary income, and the balance carries forward indefinitely. Consequently, an investor with no capital gains may take years to use a large default.
Crowdfunding Debentures Follow the Securities Rule
Crowdfunding debentures differ. Because they are transferable debt securities, a worthless debenture falls under section 165 of the Internal Revenue Code rather than the bad debt rules. The loss is treated as arising on the last day of the tax year, which can turn it into a long-term capital loss. Therefore, you must classify each failed holding correctly before you report it.
Provision Funds and Recoveries
Many platforms operate a provision fund that compensates lenders when borrowers default. For US purposes, a payment from that fund reduces your loss. If it arrives after you have already claimed a worthless-debt loss, you report the recovery as income in the year you receive it. Similarly, late recoveries from security sales must be reported, even though the UK ignores them entirely.
When the Platform Itself Fails
Several UK lending platforms have entered administration since 2019. When that happens, the loans usually remain yours, but recoveries slow down sharply and the administrator deducts its costs before paying lenders. For US purposes, you cannot claim a loss simply because the platform failed. Instead, you wait until each loan is wholly worthless or the administration produces a final distribution.
Furthermore, administration fees reduce the amount you recover rather than giving you a separate deduction. Miscellaneous itemised deductions for investment expenses remain unavailable to individuals, so platform fees and collection costs never reduce your US taxable income directly. Keep every administrator report, because the IRS expects you to show when worthlessness occurred.
Currency Gains on Sterling Loans
Every loan in your IFISA is denominated in pounds. For a US citizen, that means each loan is a foreign currency debt instrument under section 988 of the Internal Revenue Code, and exchange gains or losses arise on the principal.
How the Gain Is Measured
Your dollar basis in a loan is fixed on the day you fund it. When the borrower repays principal, you translate the repayment at the spot rate on the day it arrives. The difference between those two dollar amounts is an exchange gain or loss. Moreover, the section 988 regulations treat that gain as ordinary income, not capital gain.
Because peer-to-peer loans amortise monthly, a busy loan book can generate hundreds of small currency events each year. In practice, platform statements give you the sterling figures only, so you must build the dollar calculation yourself or have your preparer do it.
Sourcing and Credit Consequences
Section 988 gains are sourced by your residence, which for an individual means your tax home. An American living in London therefore has foreign-source exchange gains. However, Britain taxes none of that gain, because it measures everything in sterling. The currency gain on an Innovative Finance ISA is therefore fully exposed to US tax, and it can also count toward net investment income.
The 2026 and 2027 Innovative Finance ISA Rule Changes
Two sets of reforms reshape the Innovative Finance ISA for American holders. The first took effect on 6 April 2026. The second arrives on 6 April 2027.
Crypto Exchange Traded Notes Arrive, Long Term Asset Funds Leave
From 6 April 2026, cryptoasset exchange traded notes can be held only in an Innovative Finance ISA, while Long Term Asset Funds moved to the stocks and shares ISA. For a US filer, this is the most dangerous change. A crypto note is usually issued by a non-US special purpose vehicle. Depending on its terms, the IRS could treat it as debt, as a prepaid forward contract, as direct ownership of the underlying crypto or, if the note is really equity in a foreign issuer, as a PFIC.
No IRS guidance addresses UK-listed crypto notes directly. Accordingly, we read the prospectus for every note before we report it. Furthermore, UK managers do not issue the new US crypto broker form, so the reporting burden falls entirely on you.
The 22% Charge on Idle Cash From 2027
The ISA reform anti-circumvention factsheet confirms a flat 22% charge on interest paid on cash held in non-cash ISAs from 6 April 2027. The ISA manager pays the charge to HMRC, so you will not declare it. Uninvested cash sitting in your IFISA will therefore suffer UK tax for the first time.
For US purposes, the gross interest remains fully taxable. Whether you can credit the 22% depends on who is legally liable for it under UK law. Because the manager bears that liability, we expect the IRS to deny the credit, and we recommend keeping idle cash in the wrapper to a minimum.
The Cash ISA Cap and Transfer Restrictions
The same reform cuts the cash ISA limit to £12,000 for savers under 65, as set out in HM Treasury's policy paper on the cash ISA limit reduction. Transfers from an Innovative Finance ISA into a cash ISA will also be blocked for anyone under 65. Therefore, money you place in the wrapper after April 2027 is effectively locked out of cash, although you can still move it into a stocks and shares ISA.
Selling Loans Early and Moving Platforms
Most platforms let you exit early by selling loans on a secondary market. In the UK, nothing happens inside the wrapper. For US purposes, however, each sale is a disposal. A sale at a premium produces a capital gain, while a sale at a discount produces a capital loss. Moreover, if you bought a loan at a discount on the secondary market, part of any later gain can be ordinary income under the market discount rules.
A formal ISA transfer between managers is different. If the new manager takes over cash only, the US sees no disposal of loans, although the currency position continues. If the old manager sells your loans to raise the cash, you must report every sale. Therefore, ask how a transfer will be executed before you sign the form.
FBAR, Form 8938 and Schedule B Reporting for an Innovative Finance ISA
Tax is only half the problem. The other half is information reporting, and here the penalties dwarf the tax.
FBAR Reporting
An Innovative Finance ISA is an account with a UK financial institution, so it counts toward the FBAR aggregate. If the combined maximum value of all your foreign accounts exceeds $10,000 at any point in the year, you must file an FBAR through FinCEN's foreign account reporting system. Report the maximum value of the whole account, including loans outstanding and uninvested cash.
The non-wilful penalty currently reaches $16,536 per annual report. Moreover, each platform is a separate account, so an investor with three platforms has three accounts to list.
Form 8938 Thresholds and Valuation
Form 8938 applies separately. For a single filer living abroad, the threshold is $200,000 at the year end or $300,000 at any time during the year. For married couples filing jointly abroad, it is $400,000 and $600,000. The IRS comparison of Form 8938 and FBAR requirements shows how the two overlap.
You report the account itself on Form 8938, not each underlying loan. Nevertheless, you must state the maximum value, which means valuing the loan book at face value less any amounts written down. Additionally, a missing Form 8938 keeps the whole tax return open for assessment until three years after you finally file it.
Schedule B and the Foreign Account Question
Finally, Schedule B asks whether you had an interest in a foreign financial account. If you hold an Innovative Finance ISA, the answer is yes. Answering no while holding the account creates a false statement on a signed return, which is far harder to defend than a simple omission.
Records to Keep Every Year
Good records make every later step cheaper. You should keep each platform's annual statement, which shows interest credited, fees charged and the closing value. In addition, download the loan-level repayment history, because the section 988 calculation needs the date and amount of every principal repayment. Likewise, keep default notices, provision fund payments and any administrator correspondence.
We also recommend saving a note of the highest balance reached during the year for each platform. FBAR and Form 8938 both ask for the maximum value, and platforms rarely publish that figure. Rebuilding it years later from monthly statements is slow and expensive. Finally, keep these records for at least six years, because that is how long the IRS has to assess FBAR penalties.
Fixing Missed Innovative Finance ISA Reporting
If you have held a peer-to-peer ISA for years without reporting it, you are not alone. The interest is often small relative to your salary, so it gets forgotten. However, unreported foreign interest plus missed FBARs is exactly the pattern that US compliance programmes were built to resolve. Where the failure was non-wilful, the IRS Streamlined Filing route lets you file three years of amended or late returns and six years of FBARs without penalty for foreign residents.
Case Study: An American Banker With an Innovative Finance ISA
The following illustrative case study shows how the rules combine for a typical client profile. The figures are illustrative, but the mechanics are exactly what we apply on real returns.
The Client and the Portfolio
Daniel is a US citizen working as a managing director at a London investment bank. He is an additional-rate UK taxpayer and has lived in Britain for eight years. Since 2020 he has put £20,000 a year into an Innovative Finance ISA spread across three platforms, so his loan book reached £120,000. During 2025 it paid £8,400 of interest, a yield of 7%.
The US Tax on the Interest
At the 2025 IRS average rate of 0.759, Daniel's interest equals $11,067. At his 37% marginal rate, the regular federal tax is $4,095. In addition, the NIIT at 3.8% adds $421. His total US cost on the Innovative Finance ISA interest is therefore $4,516, with no UK tax to credit against it.
Had Daniel held the same loans in a taxable account, the UK would have charged 45%, or £3,780, which is $4,980. The UK credit would have wiped out the $4,095 of regular US tax, but the $421 NIIT would still apply. His combined cost would have been $5,401. Consequently, the wrapper saved him $885 in 2025. From 2027, with UK savings income taxed at 47%, the UK charge rises to £3,948 and the annual saving to about $1,100.
The Default and the Currency Gain
In 2025 one £6,000 loan became wholly worthless after the platform completed its recovery process. The UK gives Daniel nothing, because the loan sat inside his Innovative Finance ISA. In contrast, the IRS allows a $7,905 short-term capital loss. Daniel had no capital gains in 2025, so he deducts $3,000 against ordinary income and carries $4,905 forward.
Meanwhile, £40,000 of principal repaid during the year on loans he had funded in 2023, when the pound bought $1.24. The repayments arrived at an average of about $1.33. That produced a section 988 exchange gain of roughly $3,600, taxed as ordinary income at 37%, which adds $1,332 of federal tax plus NIIT. Crucially, Britain taxes none of this gain.
The Reporting Outcome
Daniel's three platforms, his UK current accounts and his pension exceeded both thresholds, so he filed an FBAR listing each platform and a Form 8938 showing each account's maximum value. He also answered yes on Schedule B. Overall, the Innovative Finance ISA still beat a taxable account for him, but only because we captured the default loss and computed the currency gain correctly. Without that work, he would have overpaid on one side and under-reported on the other.
How TaxYork Can Help
TaxYork provides comprehensive US and UK tax return preparation for high-net-worth Americans with complex British savings and investment portfolios. We translate every Innovative Finance ISA statement into US figures, classify defaults and recoveries correctly, compute section 988 exchange gains, and complete FBAR, Form 8938 and Schedule B reporting in one integrated return.
Our US tax returns for expats service covers the full federal filing, while our tax treaty optimisation work aligns your foreign tax credit baskets across salary, dividends and interest. Furthermore, our cross-border planning team reviews which wrappers genuinely suit a US citizen before you subscribe for the new tax year. For the wider picture on UK interest, read our guide to UK savings interest for US filers in Britain, and for another asset that ISA rules make worse, see our analysis of gold ETF tax for Americans in Britain.
Conclusion
The Innovative Finance ISA is tax-free in Britain and fully taxable in America, yet for an additional-rate US citizen it often remains the better home for peer-to-peer lending. The wrapper removes a 45% UK charge, rising to 47% from April 2027, while the US charge of 40.8% applies either way. However, that advantage survives only if you report the interest, capture every default as a capital loss, measure currency gains on principal and file your FBAR and Form 8938 correctly.
Meanwhile, the 2026 arrival of crypto notes and the 2027 charge on idle cash add new traps. Therefore, review your holdings before each new tax year and make sure your US preparer understands exactly what sits inside your Innovative Finance ISA.
Contact Us
If you hold an Innovative Finance ISA or any peer-to-peer lending account and want your US and UK returns prepared correctly, book a consultation with our specialist team. You can also email hello@taxyork.com or call 020 3488 8606. We handle current-year filings and missed reporting for Americans across the UK.
Disclaimer
This article provides general information about the US and UK tax treatment of Innovative Finance ISAs and peer-to-peer lending as at September 2026. It does not constitute tax, legal or investment advice, and it should not be relied upon for any specific decision. Tax rules change frequently, and your circumstances will affect how they apply to you. The case study is illustrative. Please contact a qualified US-UK tax professional before acting on any information in this article.