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HMRC has written to me about selling online

Last reviewed 31 August 2026 · How Tax Letters checks its facts

What this letter is
A nudge letter asking you to check whether your online selling counts as trading with tax to pay.
Who gets it
People whose marketplace sales data suggests they may have been trading without declaring it. The February 2025 wave covered years up to 5 April 2023, and platforms now report seller data to HMRC every January, so further waves are predictable.
Is the deadline legally binding?
Where this letter gives a reply date, the letter sets it, not the law. The deadline section below explains what that means and what ignoring it can cost.
Your options at a glance
Nothing to declare · Voluntary disclosure · Register for Self Assessment
Reply window: set by the letter, not by law

30 days from the date of the letter in the February 2025 wave.

The 30 days is set by the letter, not by statute, and HMRC can be asked for more time.

This letter states its own consequence: act within 30 days or HMRC will open a compliance check, and that can affect the penalties. Late is still far better than silent.

Source: ICAEW, 28 Feb 2025

Why you got it

Since January 2024 digital platforms have been required to collect seller information and report it to HMRC, with the first reports delivered by 31 January 2025. GOV.UK itself says a platform reporting your details does not automatically mean you owe tax.

To work out whether your selling counts as trading, and if it does, to bring your tax up to date within the letter's window, or to contact HMRC if you have nothing to declare.

Holding the letter now? Paste it into the checker for a plain-English identification.

Your options, honestly

Nothing to declare

Clearing out your own belongings is not trading. Occasional sales under the 1,000 pound trading allowance need no return. Personal items sold for under 6,000 pounds each rarely trigger capital gains tax. If this is you, contact HMRC as the letter asks and say so.

Voluntary disclosure

If you were trading, HMRC's Digital Disclosure Service is the route the letter points to. You notify, disclose and pay, and coming forward keeps you in the unprompted or best prompted position.

Register for Self Assessment

If the trading is continuing, registering going forward matters as much as fixing the past.

Standard inaccuracy penalties apply: careless errors 0 to 30 percent unprompted, 15 to 30 percent prompted, more for deliberate behaviour. Selling personal possessions is usually not taxable at all, and the trading allowance covers the first 1,000 pounds of trading income. Sources: HMRC factsheet CC/FS7a (updated 21 Jul 2026); GOV.UK digital platform guidance (updated 22 Sep 2025).

You may owe nothing

A great many recipients were only selling their own things. The letter itself allows for that: it asks you to contact HMRC and say so.

If you do nothing

The letter says HMRC will open a compliance check. Assessments can then cover 4, 6 or 20 years depending on behaviour, and penalties sit in the prompted ranges.

The letters themselves say it: if your health or personal circumstances make dealing with this difficult, you can tell HMRC and they can give you extra support. That is a standing HMRC service, and using it is normal.

Already past the date in your letter? Read this before anything else.

Questions worth asking an adviser

  • Does my pattern of selling amount to trading, badges of trade and all?
  • Which years are actually in scope, and what would each cost to put right?
  • Do the trading allowance and personal possession rules cover some or all of it?
  • Should I register for Self Assessment from now on?

Keep the date without keeping the worry

Letters like this give a reply window. Put the date somewhere that is not your head.

Want a professional to look at it?

Some letters are worth handing to a specialist, and knowing when is half the value of a check. An adviser will treat what you say in confidence and will not judge how it got here. If we cannot point you anywhere useful, we will say so.

Where to get help

You can deal with HMRC directly, free, without any adviser. If money is tight: TaxAid (low incomes, older people included) and Citizens Advice help for free.

If Tax Letters ever introduces you to a firm, the firm may pay for the introduction. You never pay Tax Letters for it, and it never changes what these pages say. How Tax Letters is funded.

Sources