HMRC disclosure routes in one paragraph: if you have undisclosed UK tax to pay, voluntary disclosure (before HMRC writes to you) generally gives the lowest penalties — often 0-30% on top of the tax owed. HMRC offers specific facilities depending on what you're disclosing: Let Property Campaign for rental income, Worldwide Disclosure Facility for offshore income, Crypto Asset Disclosure for crypto, and the general Digital Disclosure Service for everything else. Each has its own portal, scope, and terms. Pick wrong and you may pay materially higher penalties.
Why disclosure is almost always better than waiting
The penalty difference between voluntary (unprompted) and prompted disclosure is substantial:
| Behaviour | Unprompted (you came forward) | Prompted (HMRC contacted you first) |
|---|---|---|
| Careless mistake | 0-30% | 15-30% |
| Deliberate | 20-70% | 35-70% |
| Deliberate + concealed | 30-100% | 50-100% |
For a typical £20,000 underpayment due to careless omission, unprompted disclosure might cost £0 penalty (taking reasonable care defence), prompted disclosure starts at £3,000 penalty.
HMRC's information advantage in 2026 (CRS, FATCA, platform reporting, Connect AI) means undisclosed positions become discovered positions sooner. The window for unprompted disclosure narrows every year.
The five main 2026 disclosure routes
1. Digital Disclosure Service (DDS)
The default route for most undisclosed UK tax.
- Online portal: gov.uk/disclosure
- Used for: undeclared income or gains, missing tax returns, errors in past returns
- You compute the tax + interest + penalty yourself, submit, and pay
- Up to 6 years of disclosure for careless errors; 20 years for deliberate behaviour
- Penalty determined by your behavioural disclosure (telling/helping/giving)
2. Let Property Campaign
Specifically for undeclared rental income from UK property.
- Online portal: gov.uk — Let Property
- Used for: rent, holiday lets, Rent-a-Room above threshold, casual lets (Airbnb), commercial property income
- You declare the undeclared income, calculate tax/interest/penalty, and pay
- Behavioural categories same as DDS
3. Worldwide Disclosure Facility (WDF)
For undeclared offshore income, gains, or assets.
- Online portal: gov.uk — Worldwide Disclosure
- Used for: foreign bank interest, foreign dividends, foreign rental, foreign capital gains, undisclosed offshore trusts, offshore companies
- Penalty bands are HIGHER for offshore matters (territory category 1, 2, or 3)
- Up to 200% penalty for the worst category-3 offshore behaviour
- 20-year discovery window for offshore matters (vs 6 for UK)
4. Crypto Asset Disclosure
For undeclared crypto gains, income, or other cryptoasset activity.
- Online portal: gov.uk — Cryptoassets disclosure
- Used for: capital gains from disposals, mining/staking income, airdrops, DeFi yield
- HMRC's enforcement on crypto has stepped up significantly with exchange data sharing
- Particularly important for those who held large positions through 2017, 2021 peaks
5. Contractor Loan Scheme settlement
For users of disguised remuneration loan schemes.
- Specific HMRC route for "loan charge" affected users
- Includes EBTs, EFRBSs, contractor umbrella loans, "freedom" schemes
- Settlement opportunities have changed several times — current terms at gov.uk
How to choose the right facility
| If your undisclosed tax involves... | Use... |
|---|---|
| UK rental property only | Let Property Campaign |
| Offshore income (bank interest, dividends, foreign property) | Worldwide Disclosure Facility |
| Cryptoassets only | Crypto Asset Disclosure |
| Mix of UK and offshore (most cases) | WDF (broader scope) |
| Contractor loan scheme | Disguised Remuneration settlement |
| Other / unsure | Digital Disclosure Service |
| You've already had a COP9 letter | CDF only (NOT a normal disclosure route) |
The disclosure process — step by step
- Register your intent. Submit a notification through the relevant facility's portal. This protects you with "unprompted" status from that date.
- Calculate the tax. Pull bank statements, transaction records, fund statements. Compute income tax, NI, CGT, etc. for each year.
- Calculate interest. HMRC official rates compounded daily. Approximate at 3-5% per year for recent years.
- Calculate penalty. Apply behavioural reduction based on quality of disclosure.
- Submit disclosure. Online form with detailed schedules, supporting documents.
- Pay. Usually within 90 days of submission, or arrange Time to Pay.
- Receive Letter of Acceptance. Closes the matter for the disclosed period.
Worked example: Let Property Campaign
Mrs T has been renting out a flat in Birmingham since 2018 without declaring. Annual rental: £9,600. Allowable expenses (insurance, maintenance, agent fees, mortgage interest): £4,000 net = £5,600 profit per year. She's a higher-rate taxpayer.
She makes voluntary unprompted disclosure in May 2026.
- Years covered: 2018/19 to 2024/25 (7 years; HMRC accepts 6-year disclosure for careless, but she goes back further voluntarily)
- Total undeclared profit: 7 × £5,600 = £39,200
- Tax due (40% higher rate): £15,680
- Interest (approx. 3-5% compounded): £3,500
- Penalty (careless, unprompted, full cooperation, 10% rate): £1,568
- Total to pay: £20,748
If she'd waited for HMRC to contact her (which would have happened — HMRC matches Land Registry and council tax data routinely), penalties would have been ~30% = £4,704 instead of £1,568. Difference: £3,136 saved by voluntary disclosure.
What happens after disclosure
HMRC reviews the disclosure within 3-6 months. Possible outcomes:
- Acceptance as submitted. Most cases. Letter of Acceptance issued; matter closed.
- Request for further information. HMRC has questions; you respond.
- Counter-proposal. HMRC believes the disclosure undercalculated. They issue an alternative calculation.
- Rejection. Rare; only if HMRC believes you've materially misrepresented the matters disclosed.
The Letter of Acceptance protects you for the disclosed matters — they can't be reopened later unless HMRC discovers fraud not disclosed.
Common disclosure mistakes
- Wrong facility. Disclosing offshore income via the general DDS instead of WDF can be problematic — penalty ranges differ.
- Under-disclosing. Cherry-picking what to admit. HMRC's data may already show more — partial disclosure can be worse than none.
- Over-disclosing. Volunteering matters that fall outside the scope of HMRC's discovery window or that you have no obligation to disclose.
- Calculating tax wrongly. Especially capital gains pooling, foreign tax credits, allowable expenses. Errors lead to HMRC counter-calculations and disputes.
- Not engaging professional advice on complex cases. Disclosures >£25k of tax usually warrant adviser involvement.
- Disclosing after a nudge letter without realising it's now "prompted". Once you've been written to, the unprompted rates no longer apply.
Sources
Related HMRC enquiry content
How UK Tax Drag holds itself to account
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