Received an HMRC Letter About Your Online Sales? Here’s What You Need to Know

HM Revenue & Customs (HMRC) has confirmed that between 6 July and 31 August 2026, it may automatically register certain individuals for Self Assessment where its data suggests they may have received untaxed income from online selling, social media platforms or card payment transactions.

If you receive one of these letters, don’t panic—and don’t assume you automatically owe tax.

Why is HMRC contacting people?

HMRC now receives more information from online marketplaces and payment platforms than ever before. If its records indicate that you may have earned taxable income, it may register you for Self Assessment and ask you to complete a tax return.

However, automatic registration is not evidence that tax is actually due.

Selling online doesn’t always mean you’re trading

One of the first questions is whether your activity amounts to a business or simply selling unwanted personal belongings.

Generally:

Selling second-hand personal possessions for less than you originally paid is not normally taxable.
Regularly buying goods to resell for profit is more likely to be considered trading.
Each case depends on the facts and circumstances.

Questions you should consider

If you’ve received an HMRC letter, it’s important to establish:

Are you actually trading?
What were your total sales?
What business expenses can you claim?
Does the £1,000 Trading Allowance apply?
Do any earlier tax years need to be disclosed?
Has HMRC received duplicated or incorrect information?

Don’t ignore the letter

Ignoring HMRC correspondence could lead to unnecessary penalties or further enquiries.

Equally, don’t submit an incorrect tax return simply because HMRC has registered you for Self Assessment.

Before filing anything, it’s important to establish whether a tax return is actually required and ensure any figures submitted are accurate.

How SKN Chartered Accountants can help

If you’ve received an HMRC letter relating to online sales, eBay, Vinted, Etsy, Amazon, Shopify, TikTok Shop or other digital platforms, we can:

Review whether your activity is taxable
Calculate any profits correctly
Apply available reliefs and allowances
Deal directly with HMRC on your behalf
Correct any inaccurate HMRC assumptions
Minimise penalties where appropriate

Early professional advice can often prevent small issues becoming costly enquiries.

Need advice? Contact SKN Chartered Accountants for expert guidance before responding to HMRC.

https://www.gov.uk/register-for-self-assessment

https://www.gov.uk/guidance/sign-up-for-making-tax-digital-for-income-tax