Concept
Cleanup is a legal reconstruction of past tax years, not a cosmetic amendment to match a bank balance. It identifies the correct residence, income, gains, trust, company and disclosure positions for each year before anything is said to HMRC. The order matters: facts first, quantification second, disclosure route third.
HMRC receives offshore information through the Common Reporting Standard and related exchange systems described in IEIM400080. From 1 January 2026 the Cryptoasset Reporting Framework extends the same reporting logic to crypto, with the first international exchanges due in 2027. Where offshore income or gains were not reported correctly, HMRC's Worldwide Disclosure Facility is one official route, run through the Digital Disclosure Service with a 90-day window to complete a notified disclosure. The general route for other liabilities is HMRC's voluntary disclosure guidance.
Scope
Cleanup reaches omitted foreign income, unreported gains, offshore accounts, non-reporting funds, trust benefits, company distributions, CRS mismatches, late residence corrections and prior remittance-basis problems. It does not handle criminal defence in detail, but conduct and intent must be assessed early because they drive the route and the penalty exposure.
The chronological test
The analysis is year by year. For each open year: determine residence; identify foreign income and gains; test reliefs and treaties; identify trust or company attribution; compare with the return filed; quantify tax, interest and penalties; decide the disclosure route; and preserve privilege where appropriate.
| Step | Question for each year |
|---|---|
| Residence | UK resident, non-resident or split-year under the Statutory Residence Test |
| Income and gains | which foreign income and gains arose, and whether they were taxable in the UK |
| Attribution | trust or company income and gains attributed to the settlor or beneficiary |
| Comparison | what the return filed actually reported against the reconstructed position |
| Quantum | tax, interest and penalty exposure, including offshore penalty categories |
| Route and conduct | amended return, WDF or other route, assessed against carelessness or deliberate behaviour |
Outcomes and risk
The outcome may be an amended return, a WDF disclosure, a negotiated penalty position, an enquiry response, or a decision that a more formal route is required. The posture turns on carelessness, reasonable excuse, deliberate conduct, the offshore category and the quality of evidence.
Controlled cleanup
Scope, years, taxes, conduct and route are defined before contact. Current-year compliance is aligned so the repair does not create a fresh contradiction. Bank data, CRS records and trust and company facts are reconciled into one position.
The recurring failures
A partial disclosure before the facts are known; treating bank data as complete while trusts, companies, funds and crypto wallets also exist; and ignoring years that look closed but stay open under offshore time limits or because behaviour was deliberate.
Examples
A client finds CRS reports for Swiss dividends omitted from the foreign income pages. A former remittance-basis user remitted pre-2025 foreign income without treating it as taxable. A trust beneficiary received offshore benefits that were neither matched nor reported. A crypto investor reported exchange cash-outs but not token-to-token disposals, the kind of transaction the Cryptoasset Reporting Framework starts reporting to HMRC from 2026.
Order of the repair
The sequence follows what each step depends on. The open years are settled before anything is drafted, including the years that stay open under offshore time limits, and residence, income, gains, trust and company positions are reconstructed year by year across that span.
Bank data, CRS records, fund statements and crypto exports are then reconciled into a single schedule, and tax, interest and penalties are quantified against it together with the conduct category. Only on that basis does the disclosure route follow from the facts — an amended return, the Worldwide Disclosure Facility or another official route — with current-year compliance aligned so that the repair does not create a new inconsistency.
Common mistakes
- Making a partial disclosure before the full fact pattern is known.
- Treating CRS or bank data as the complete picture.
- Assuming a year is closed when offshore time limits or deliberate behaviour keep it open.
- Amending figures to match a bank balance without the legal analysis behind them.
- Repairing old years while filing a current-year return that contradicts the cleanup.
Advisor trigger
A tax adviser can run a straightforward amended return where the error is small and the conduct is plainly careless. A UK tax lawyer should lead where there is deliberate conduct, potential willfulness, a possible criminal dimension, large or multi-year offshore exposure, trust and company attribution, or any need to preserve legal privilege.
What HMRC already knows
By the time a file is rebuilt, HMRC usually holds the data already. The Common Reporting Standard feeds it balances, dividends and disposal proceeds from more than a hundred jurisdictions; FATCA covers US-linked accounts; and from 2026 the Cryptoasset Reporting Framework adds exchange and wallet activity. That feed is set out in the note on what HMRC receives under CRS and FATCA. The working assumption is that the counterparty data already exists, so a disclosure should be built to match the record HMRC can see rather than to introduce something it does not.
Time limits that decide the work
How far back the repair reaches is set by statute rather than by how many years of statements survive. The ordinary assessment window is four years. Careless errors extend it to six, and for offshore income, gains and chargeable transfers the Finance Act 2019 took the limit for careless or innocent errors to twelve years across income tax, capital gains tax and inheritance tax (TMA 1970 s 36A; IHTA 1984 s 240B). The twelve-year limit does not apply where, before the ordinary limit ran out, HMRC received overseas information — CRS data, for example — from which it could reasonably have been expected to spot the loss of tax and assess in time. Deliberate behaviour reaches twenty. Conduct sets both the penalty and the number of years in scope, which is why it is assessed before anything is quantified.
A discovery assessment must itself clear two hurdles. The officer must genuinely "discover" the loss of tax — hold a reasonable belief that tax has been under-assessed — and one of the s 29 TMA 1970 gateway conditions must be met: the loss was brought about carelessly or deliberately by the taxpayer or someone acting on their behalf, or a hypothetical reasonable officer could not have seen the problem from the information made available by the time the enquiry window closed — the return, the accounts and documents sent with it, claims, and documents produced in an enquiry. The burden of proving carelessness rests on HMRC, and tribunals discharge assessments where it is not met — so the conduct category governs not only the time limit but the validity of the assessment itself.
Penalties and the disclosure routes
Offshore penalties are heavy by design. The Failure to Correct regime reaches offshore non-compliance committed on or before 5 April 2017 and not put right by the 30 September 2018 deadline: the penalty is 200% of the tax, reducible for disclosure to no less than 100%, whatever the territory. The territory category loads the ordinary offshore penalties instead: for deliberate and concealed conduct the maximum is 100%, 150% or 200% of the tax in categories 1, 2 and 3, set by a 2011 Treasury designation order rather than by CRS participation. A full, accurate and unprompted disclosure earns the largest reduction; that credit narrows once HMRC already holds the data, and a delay of more than three years is normally treated as a significant period that limits relief. The Worldwide Disclosure Facility, made through the Digital Disclosure Service, opens a 90-day window once a disclosure is notified.
Where HMRC suspects deliberate fraud it does not offer the Worldwide Disclosure Facility. It issues Code of Practice 9 under the Contractual Disclosure Facility: 60 days to admit deliberate conduct and disclose it in full, in return for immunity from criminal prosecution on the matters disclosed. Picking the wrong route, or making a partial disclosure inside any of them, is what turns a manageable position into a contested one.
Cleanup after the 2025 reset
The 2025 reform changed what cleanup examines. Domicile was removed as a connecting factor, the remittance basis closed on 6 April 2025, and a residence-based Foreign Income and Gains regime replaced it. Most historic files now hold a mix of old remittance-basis years and the new rules, and the two have to reconcile rather than contradict. The Temporary Repatriation Facility runs alongside the repair: former remittance-basis users can designate pre-6 April 2025 foreign income and gains at 12% for 2025/26 or 2026/27 and 15% for 2027/28, paid through self-assessment. The facility covers only remittance-basis income and gains that had not been brought to the UK before 6 April 2025, together with overseas funds of uncertain origin: tax on remittances made before that date is corrected at the ordinary rates. A cleanup that ignores the facility can miss the chance to settle the still-unremitted balance at the lower rate.
Q&A
Is WDF the only disclosure route
No. The Worldwide Disclosure Facility is one official route for offshore income or gains. The correct route depends on the years, the tax type, the conduct, and whether the returns can still be amended.
Should a client wait for HMRC to ask
Not usually, where a known offshore error exists. Delay can worsen the penalty position and damage credibility once HMRC already holds CRS data. But the disclosure should follow the facts, not precede them.
Can CRS data be wrong
Yes. A mismatch can come from classification or reporting error. It still needs an explanation supported by evidence, because HMRC works from the data it received until the record shows otherwise.
Can a partial disclosure backfire
Yes. Disclosing one account or one year before the full pattern is known can create contradictions with later facts, undermine the conduct argument and increase the penalty exposure.