1. Establish what HMRC already holds
Create a separate row for every potentially affected tax year. Record the trade, income sources, whether you had a UTR, whether HMRC issued a notice to file, whether a return was submitted and any payments made. Obtain filed returns and acknowledgements rather than relying on old drafts.
Keep HMRC letters, dates and deadlines together. Tell your adviser about any existing enquiry or request for information immediately. Do not assume that receiving no recent letter means a year is settled.
2. Reconstruct the figures by year
Gather contracts, invoices, platform reports, bank statements and expense evidence. Reconcile customer receipts, refunds and fees, identifying transfers and loans separately. Use our sole-trader reconciliation guide for the evidence method, while checking the rules applicable to each earlier year.
Include income and tax already reported elsewhere, such as PAYE earnings, in the review. Additional tax cannot reliably be calculated by applying one flat percentage to total omitted receipts. Record missing evidence and assumptions explicitly.
3. Select the correction or disclosure route
A return still within its amendment window can normally be corrected through that route. HMRC generally permits amendments within 12 months of the Self Assessment deadline. Outside that window, or where no return was filed, the route needs separate review.
HMRC provides several disclosure facilities and specific campaigns. Offshore matters, rental income and deliberate conduct can require different consideration. A digital disclosure is not automatically the right answer for every case. Do not put all historic income into the latest return simply to clear the backlog.
4. Act promptly and understand the timetable
HMRC asks taxpayers to report undeclared taxable income as soon as possible. A voluntary approach can affect penalty treatment, but it does not guarantee that penalties will be waived. The years to review and the tax, interest and potential penalties depend on the facts.
If the digital disclosure service is appropriate, HMRC normally requires the completed disclosure within 90 days of its notification acknowledgement, with payment or agreed payment arrangements in place as required. Prepare records early and obtain advice before choosing the route, without using preparation as a reason to delay necessary notification.
5. Address affordability alongside the calculation
Prepare a realistic summary of income, essential spending, assets and other debts if full payment may be difficult. HMRC can consider instalments and assesses affordability. Approval and the terms are not guaranteed.
Keep current-year records and filing obligations moving while earlier years are resolved. A repayment discussion is not a substitute for declaring the income or meeting a filing deadline.
Request a defined initial review
Tell us the activity, approximate years affected, whether returns were filed and whether HMRC has contacted you. Keep sensitive documents out of the initial website message; we arrange an appropriate secure route after scoping.
UA Tax supports London and UK-wide clients with HMRC enquiry and disclosure advice. Earlier-year reconstruction and disclosure fees are agreed for the work required. Get in touch to discuss the starting point. We cannot promise a particular HMRC outcome.
For advice on your own circumstances, see our earlier-year income review service and agree the scope before acting.
Official sources and further reading
These primary sources support the framework above. Check the current version before acting because tax law and HMRC guidance can change.