UK Self Assessment Tax Returns Explained

If you are living and working in the UK, you might be required to file a UK Self Assessment tax return. However, the rules for this form of income tax are complex. We’ve written this guide to help you understand whether you’re required to file—and how you can comply if you are.

Who Is Required to File a UK Self Assessment Tax Return?

Most residents of the UK are required to file a Self Assessment tax return if any of the following are true:

• You earn at least £100,000 in taxable income
• You or your partner earns at least £50,000 and you claim Child Benefit
• You are self-employed
• You are a partner in a business partnership
• You earn more than £2,500 in untaxed income (this income may include tips, rental income, or foreign income)
• You are a company director (this does not apply if you received no compensation at all for your role, including benefits like a company car)
• You earn more than £10,000 before tax from savings, investments, or dividends from shares
• You owe capital gains tax
• You earn money from the UK while living in another country

This list is not comprehensive, and the question of who has to file a UK Self Assessment tax return can be complicated and nuanced. Consult a qualified expat tax professional to learn the details of your specific situation.

Deadline for Filing a Self Assessment Tax Return

Unlike the US, the UK tax year runs from April 6 to April 5 of the following year. The deadline for filing a Self Assessment tax return will depend on how you file.

• If you file a paper return, the deadline is October 31
• If you file your return online, the deadline is January 31

Regardless of how you file, you will usually need to pay any taxes you owe on your Self Assessment tax return by January 31. However, this is only if you choose to pay your tax debt in one lump sum. You can instead opt to spread the payment out into two or more installments, which will change the deadline.

Registering for a Self Assessment Tax Return

If you’ve never filed a UK Self Assessment tax return, you’ll need to register first. There are different ways to register depending on whether you’re employed, self-employed, or part of a partnership.

See the official website of the UK government to learn more.

Filing a Self Assessment Tax Return

Once registered, you’ll receive a Unique Taxpayer Reference (UTR) number from HMRC, the UK tax authority. You can then use your UTR number to register for a Government Gateway account.

After creating your Government Gateway account, you will receive an activation code by mail. This will allow you to file your UK Self Assessment tax return online using the Government Gateway.

There are two other options for filing the Self Assessment tax return. You can use tax software to complete your turn. (See here for a list of options.) Alternatively, you can file your form the old-fashioned way: pen and paper. Download Form SA100, fill it out by hand, and mail it to HMRC.

Paying a Self Assessment Tax Bill

Once you’ve filed your Self Assessment tax return, you can pay the amount you owe in a number of ways, such as:

• Online
• By phone
• By mailed check
• At a bank or building society
• Through CHAPS

If you pay at a bank or building society, you will need a paying-in slip from HMRC.

Note: While paying at a post office used to be allowed, this option is no longer available.

Still Have Questions? We Have Answers!

We hope this guide has helped you understand your UK Self Assessment tax return. If you still have questions, we’d be happy to answer them. We can also prepare and file your US expat taxes on your behalf.

At Greenback Expat Tax Services, we help expats around the world file their US taxes accurately and on time. Just contact us, and we’ll help you in any way we can.

Contact us today to get answers to all your expat tax questions.