SideLedger › Guides › Telling HMRC about past sales

Telling HMRC About Past Online Sales: Disclosure Guide

Checked 28 Oct 2026 against GOV.UK · General information, not tax advice

Who this guide is for

This is for online sellers who haven't had a letter from HMRC but think they may have income from past years that they should have declared. If HMRC has already written to you about your sales, follow the letter and see our guide to getting an HMRC letter about Vinted or eBay sales instead. HMRC's guide also says that if you qualify for a current HMRC campaign, you should follow that campaign's guidance (HMRC: Your guide to making a disclosure).

Step 1: Check whether you had anything to declare

Many people who sell online have nothing to declare. GOV.UK says (GOV.UK):

• "You're unlikely to pay tax if you sell personal items from your home, like contents of a loft or garage."
• "If you buy or make goods to sell at a profit, you're likely to be trading and will have to pay tax on your profits."

GOV.UK's undeclared income page lists, as income you may need to tell HMRC about, "working for yourself, including if you buy or sell items regularly, for example at car boot sales or on the internet" (GOV.UK: Tell HMRC about undeclared income). If you were trading, small amounts were covered by the trading allowance for the years it applied. Our guide to HMRC's badges of trade explains how HMRC decides, and HMRC's free checking tool can help.

Work it out tax year by tax year (6 April to 5 April), not by the calendar-year totals platforms show you.

Step 2: Gather your records

HMRC's guide says that if your records are incomplete, you can use estimates, but keep a note of how you worked them out. It also says you'll need your bank statements (HMRC). For online selling, useful records include:

• each platform's sales history or downloads, and any reports a platform sent you
• bank and payment statements
• receipts or notes of what you paid for stock, postage and fees

Our free profit tracker spreadsheet has a tab for each tax year, which can help you rebuild past years.

Step 3: Choose the right route

From GOV.UK (undeclared income, HMRC disclosure guide):

• The current or last tax year: HMRC's disclosure guide says income for these years goes on a tax return, not a disclosure, and if you're not registered you'll need to register now. If you'd already sent a return, HMRC says you can amend it within 12 months of the statutory filing date.
• You're registered for Self Assessment but haven't declared all your income: GOV.UK says you can make a change to your return.
• You don't usually send a tax return: GOV.UK's undeclared income page says you can register for Self Assessment to declare income you haven't paid tax on from the last 4 years, with a separate tax return for each year.
• Earlier years: HMRC's online Digital Disclosure Service covers taxes including Income Tax, Capital Gains Tax and National Insurance, but not VAT. HMRC's guide says you can use it for tax years up to and including 2024 to 2025. HMRC's guide gives "a business that's trading and has not registered" as an example of what it covers.

If you're not sure which applies to you, HMRC has a helpline for voluntary disclosures where HMRC hasn't contacted you: 0300 123 1078 (HMRC). An accountant or tax adviser can help too.

Step 4: Using the Digital Disclosure Service, step by step

HMRC's guide sets out these steps (HMRC: Your guide to making a disclosure, GOV.UK: Tell HMRC about underpaid tax from previous years):

1. Notify HMRC. You sign in and tell HMRC you're going to make a disclosure, as soon as you know you owe tax. You don't need to give the details at this stage. You'll need your National Insurance number, and your Unique Taxpayer Reference if you have one.
2. Get your references. HMRC acknowledges your notification and sends you a disclosure reference number and a payment reference number.
3. Make your disclosure. HMRC must get your disclosure and payment within 90 days of its acknowledgement. You work out the extra income and tax for each year, plus interest, and HMRC's guide says it's you who must work out any penalty, using HMRC's penalty factsheets.
4. Make a formal offer. Your disclosure includes an offer to pay what you've calculated.
5. Pay. HMRC expects payment, using your payment reference, at the same time as your disclosure. Its guide says that if you can't pay the full amount, call the helpline before you submit your disclosure. See also GOV.UK: If you cannot pay your tax bill on time.
6. Answer any questions. HMRC may check your disclosure and ask for more information.

How many years it covers

HMRC's disclosure guide says how far back you go depends on why the tax wasn't paid (HMRC):

• Up to 4 years if you took reasonable care
• Up to 6 years if you were careless
• Up to 20 years if it was deliberate, or if you didn't register for Self Assessment by the deadline

On that last point, HMRC's guide says you should tell HMRC about a new business by 5 October in the business's second tax year. So if you started trading on Vinted or eBay above the trading allowance and never registered, read the guide carefully or get advice. Which category applies isn't something you just choose; HMRC looks at the facts.

What you'll pay on top of the tax

HMRC's guide says interest is charged on tax paid late, from the date it was due. It also says penalties are usually lower if you tell HMRC yourself, and that if you took reasonable care there's no penalty at all, though HMRC adds that it doesn't expect many people's circumstances to fall into that category. HMRC has a penalties and interest calculator for individuals, which it says to use only if your tax affairs are straightforward (HMRC). We've left out percentages and rates on purpose: use HMRC's own calculators and guidance on the day you disclose.

After you've told HMRC

• If you're still trading above the trading allowance, make sure you're registered for Self Assessment going forward: see our reseller Self Assessment guide.
• Keep records as you go. It's much easier than rebuilding years later, which is what SideLedger is being built to help with.
• If your health or circumstances make dealing with HMRC hard, ask about HMRC's extra support.

Budget 2026

We checked everything on this page on 28 October 2026, the day of the Budget. HMRC says full details of the Budget's tax announcements are published on GOV.UK that day (GOV.UK: Budget 2026 tax documents). We've deliberately avoided tax rates, interest rates and penalty percentages, which can change. Use HMRC's own calculators and guidance when you disclose. We'll re-check this page against the published Budget documents.

Quick answers

How do I tell HMRC about past online sales income?

GOV.UK says to tell HMRC as soon as possible. If you're registered for Self Assessment, you may be able to amend a tax return. For older years, HMRC's Digital Disclosure Service lets you notify HMRC, then disclose the income and pay within 90 days. GOV.UK's undeclared income page also says that if you don't usually send a tax return, you can register for Self Assessment to declare untaxed income from the last 4 years.

What is the HMRC Digital Disclosure Service?

It's HMRC's online service for telling it about tax you owe from previous years. It covers taxes including Income Tax, Capital Gains Tax and National Insurance, but not VAT. You notify HMRC first without giving details, get a disclosure reference number, then have 90 days to make your disclosure, an offer and payment.

How far back does HMRC go for undeclared online sales?

HMRC's disclosure guide says up to 4 years if you took reasonable care, up to 6 years if you were careless, and up to 20 years if it was deliberate or if you didn't register for Self Assessment by the deadline. HMRC decides which applies to you.

Do I need to tell HMRC if I only sold my own things?

Usually not. GOV.UK says you're unlikely to pay tax if you sell personal items from your home. Check whether you were trading first, using HMRC's free checking tool.

Not sure where you stand?

• Use HMRC's free tool: Check if you need to tell HMRC about additional income.
• Read GOV.UK's guide to telling HMRC about income from online platforms.
• Speak to an accountant or tax adviser. If you're on a low income, the charity TaxAid gives free tax help.

Sources

• GOV.UK: Tell HMRC about undeclared income
• HMRC: Your guide to making a disclosure
• GOV.UK: Tell HMRC about underpaid tax from previous years (Digital Disclosure Service)
• GOV.UK: Selling goods or services on a digital platform
• GOV.UK: Tax-free allowances on property and trading income
• GOV.UK: Register for Self Assessment
• GOV.UK: If you cannot pay your tax bill on time
• GOV.UK: Budget 2026 tax documents

More guides for UK online sellers

• Do You Pay Tax on Vinted? UK Rules & HMRC Limits 2026 – Own clothes vs reselling, the £1,000 allowance and the 30-sale reporting rule, in plain English.
• Vinted HMRC Form & NI Number Request: What to Do – Why Vinted is asking for your National Insurance number, the end-of-year deadline, and why it doesn't mean you owe tax.
• Vinted Tax Calculator UK: Free HMRC Limit Checker – Check your sales against the 30-sale / ~£1,700 reporting rule and the £1,000 allowance. It checks limits; it doesn't work out a tax bill.
• eBay HMRC Reporting Threshold 2026: £1,707 or 30 Sales – What eBay counts towards £1,707, what it reports, and why a report isn't a tax bill.
• Got an HMRC Letter About Vinted or eBay Sales? What to Do – A calm step-by-step: check it's genuine, work out if you were trading, and reply on time.
• Free Vinted & eBay Profit Tracker Spreadsheet (UK) – A free download with tax-year tabs, profit per item and a check against the HMRC limits.
• Trading Allowance vs Expenses: Which Should Resellers Use? – The £1,000 allowance or your real costs? Why resellers who track stock costs often come out ahead with expenses.
• Do Resellers Need to Register for Self Assessment? – When reselling counts as trading, the £1,000 rule, and the 5 October and 31 January deadlines.
• Depop HMRC Reporting: Do You Pay Tax on Depop Sales? – What Depop reports, what it asks you for, and Depop's own example of being reported but owing no tax.
• Etsy UK Tax: HMRC Reporting Rules for Sellers 2026 – When Etsy reports you to HMRC, and why things you make to sell usually count as trading.
• The £3,000 Side Hustle Threshold: Not in Force Yet – What was announced, what it would change, and why the £1,000 rule still applies today.
• Why Is eBay Asking for My National Insurance Number? – Why eBay wants your NI number, what happens if you don't give it, and why giving it doesn't mean you owe tax.
• Selling Personal Items on eBay: Do You Pay Tax? (UK) – Clear-outs vs trading, the £6,000 Capital Gains Tax rule for valuable items, and why eBay may still report you.
• Facebook Marketplace & HMRC: Do They Report You? – What we could and couldn't confirm about Facebook Marketplace reporting, what Gumtree says, and why the tax rules are the same either way.
• Am I Trading? HMRC's Badges of Trade for Resellers – HMRC's nine badges of trade with Vinted and eBay examples, plus car boot sales: when selling becomes trading.
• Vinted Pro vs Personal Account: Does It Change Tax? – What Vinted says about Pro and standard accounts, what HMRC actually looks at, and why switching account type isn't what decides tax.