When to get professional help

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Situations where advice often pays

You can claim many losses yourself using the guides on this site. It is worth considering professional help when:

• the loss is large, or several reliefs compete for the same years (for example sideways relief against the cap);
• a business is starting or stopping — choosing between early years, sideways, carry-forward and terminal relief can change the tax a lot;
• you are a limited or non-active partner, an LLP member, or the loss involves a company or group;
• there is an overseas element, or you’re non-resident;
• shares in a failed company may qualify for share loss relief;
• a deadline is close, or HMRC has opened a compliance check.

Who can help

HMRC. HMRC’s contact pages list helplines for Self Assessment and for Capital Gains Tax enquiries. They can help with your returns, payments and records, but they won’t tell you which claims would save you the most.

Free help. GOV.UK’s guidance mentions charities and Citizens Advice. TaxAid runs a free helpline for people who can’t access professional tax advice; its website says that in most cases it can only help people earning under £30,500, and that it can’t help with Corporation Tax. Tax Help for Older People merged into TaxAid in July 2025, according to its own website. LITRG (the Low Incomes Tax Reform Group) publishes free guidance, though it doesn’t give individual advice.

Qualified advisers. The Association of Taxation Technicians (ATT), the Chartered Institute of Taxation (CIOT — Chartered Tax Advisers), ICAEW and ACCA all run directories of their members.

Links to all of these are on our help page.

Choosing an adviser

GOV.UK’s guidance on choosing a tax agent warns that anyone can call themselves a tax agent — they don’t need qualifications, and HMRC doesn’t regulate agents. Sensible checks:

• Are they a member of a professional body, and do they appear in its directory?
• Do they deal with your kind of loss (investments, a trade, property, a company)?
• What will they charge, and what exactly is included?
• Will they act as your agent with HMRC? You authorise an agent through GOV.UK.

GOV.UK also notes that you don’t need an agent to claim a tax refund, and that you can authorise a friend, relative or voluntary organisation to talk to HMRC for you.

Questions people ask

Where can I get free help with a tax loss?

TaxAid runs a free helpline for people who can’t afford professional advice (its website says it usually helps people earning under £30,500, and that it can’t help with Corporation Tax). Tax Help for Older People is now part of TaxAid. LITRG publishes free guidance. See our help page.

Sources

Checked 4 October 2026 for the 2026/27 tax year. We read these primary sources for this guide:

1. GOV.UK: How to choose a tax agent (gov.uk)
2. GOV.UK: Appoint someone to deal with HMRC on your behalf (gov.uk)
3. GOV.UK: Self Assessment — general enquiries (gov.uk)
4. GOV.UK: Capital Gains Tax — enquiries (gov.uk)
5. GOV.UK: HMRC compliance checks — help and support (gov.uk)

Contains public sector information licensed under the Open Government Licence v3.0. This guide adapts and summarises that information in our own words. taxloss.co.uk is an independent guide. It is not affiliated with, endorsed by or connected to HM Revenue & Customs (HMRC) or the UK Government. Spotted something out of date? Tell us.

More on returns, deadlines & records

• 19Deadlines for loss claimsEvery loss relief has a time limit, and they aren’t all the same. Some run 4 years from the end of the tax year; some only to the first anniversary of the 31 January filing date. Here are the main ones in one place, with the 2026/27 dates.
• 20Where losses go on your Self Assessment returnA plain-English map of the loss boxes on the Self Assessment supplementary pages — capital gains (SA108), self-employment (SA103), partnership (SA104), UK property (SA105) and additional information (SA101). Box numbers are from the 2025–26 forms.
• 21Amending a return or claiming laterForgot to claim a loss? You can usually amend your Self Assessment return within 12 months of the 31 January deadline. After that, many loss claims can still be made by letter within their own time limits — and overpayment relief is available for up to 4 years.
• 22Making Tax Digital for Income Tax from April 2026Since 6 April 2026, sole traders and landlords with qualifying income over £50,000 must keep digital records, send quarterly updates and file their tax return through compatible software. Here’s who is affected, when, and what GOV.UK says about losses.
• 23Records and evidence HMRC may ask forTo claim a loss you need to be able to show how you worked it out. What to keep for capital losses, crypto and business losses, how long to keep it, and what HMRC can ask for in a compliance check.