How and when to register for Self Assessment
A guide to registering for Self Assessment for untaxed income
Registering for Self-Assessment is how HMRC sets you up to report personal income that has not already been taxed at source. It is separate from your company's own registrations.
When to register
If you need to file, you must register by 5 October following the end of the tax year in which you first had income to report, for example the first year you received dividends above the dividend allowance. So, if your first dividends fell in the 2025/26 tax year (ending 6 April 2026), you would register by 5 October 2026. If you are on our Accounting Standard or Scale plan, or have added Self Assessment to your plan, we handle this registration for you as part of onboarding. Otherwise, registering is your responsibility, and you can do this through your HMRC online account.
What HMRC sends
After you register, HMRC posts a personal Unique Taxpayer Reference (UTR) to your home address. Your personal UTR is a 10-digit number used on all your personal tax correspondence. Keep it safe. Where we handle your personal tax, we use it to file your return and to deal with HMRC on your behalf.
💡 Good to know: Your personal UTR is different from your company's UTR. Both are ten digits but relate to different taxpayers, so it is easy to mix them up. If your plan includes Self Assessment, forward any HMRC letters you receive to us, clearly indicating whether they relate to you personally or to the company.
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