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From 6 January 2024, the main rate of class 1 National Insurance contributions (NIC) deducted from employees’ wages is reduced from 12% to 10%. From 6 April 2024, the main rate of self-employed class 4 NIC will reduce from 9% to 8% and class 2 NIC will no longer be due. Those with profits below £6,725 a year can continue to pay class 2 NIC to keep their entitlement to certain state benefits. Our guidance will be updated in full in spring 2024.

Updated on 6 April 2023

Registering for self assessment

Registering for self assessment refers to the process by which HMRC issue you with a unique taxpayer reference (UTR) (if you don’t already have one) and they send you a formal notice to file a tax return for a year. If you need to send a self assessment tax return for the first time, you will need to register with HMRC for self assessment.

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How to register

There are different ways to register depending on your circumstances. If you are self-employed, see our separate guidance.

If you are not self-employed, see the guidance on GOV.UK.


If you need to notify HMRC that you owe tax for a year (see Who has to complete a tax return), you must do so by 5 October following the end of the tax year. For example, if you received rental income in the 2022/23 tax year, you should register with HMRC by 5 October 2023.

How do I register for self assessment? Calendar timeline shows tax year starting 6 April 2023, Joe starting a business on 1 January 2024, the tax year ending on 5 April 2024 and Joe then having to notify HMRC of a new tax liability by 5 October 2024.

The above deadline does not apply where HMRC have already asked you to file a tax return for the year. For example, if you already file tax returns for another reason but you start to receive a new source of income, then you would usually just report that new source of income on the relevant return (though you may need to register separately for class 2 National Insurance if you commence self-employment).

If you miss the notification deadline, then you may be charged a penalty for failure to notify.

However, if you notify HMRC after 5 October, then provided you have paid your income tax liability in full by the usual 31 January payment deadline, HMRC should reduce the late-notification penalty to zero. Note in these circumstances that you should also make sure you file your tax return on time.

If you have reported a property disposal within 60 days, you may still need to register separately for self assessment.

If you already have a UTR

If you already have a unique taxpayer reference (UTR) – perhaps because you filed tax returns some years ago – then you should still notify HMRC by the 5 October deadline if you need to file a tax return for the previous year.

HMRC will then issue a formal notice to file a tax return for the previous year.

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