7 tips for filing your 2022-23 tax return by the deadline

Self-assessors have just a couple of days left to file their 2022-23 tax return before the final deadline of midnight on 31 January.

Last week, the tax office said it was still waiting for 3.8 million people to file their online returns. Failing to submit a self-assessment on time will land you with a £100 fine. Wednesday is also the deadline for paying your bill to HMRC, with late payment interest currently set at 7.75%.

But if you've left it to the last minute, don't panic. Here, Which? provides seven tips to help you get your 2022-23 tax return done before the clock strikes 12.

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1. Gather all your documents

Before you start, make sure you have everything you need to file an accurate return and keep them close at hand. By doing so, you'll feel more confident about the task ahead and are less likely to make a mistake.

Your National Insurance number and Unique Taxpayer Reference (UTR) number are essential, but other important documents to remember are your P60 form (if you’re employed), relevant receipts and invoices, bills, bank statements, tenancy agreements, student loan statements and details of any benefits. 

• Find out more: how to fill in a self-assessment tax return

2. Get ready to login

Once you have organised all your paperwork, it's time to take the plunge. To start the filing process, you'll need to log in to the government website. It will ask you to enter your government gateway ID and password, so make sure you have these details ready to avoid last-minute scrambling around looking for them.

If you can't find them or have forgotten them, don't worry, they can be reset. You might have to wait a little for the new login details to come through, so it's best to get the ball rolling now while you still have a couple of days to spare before the deadline. 

3. Remember to make use of allowances and expenses

Taking full advantage of tax reliefs and allowances can knock significant sums off your bill. We’ve outlined some of the main ones to be aware of below:

• Self-employed business expenses: HMRC allows you to deduct legitimate business expenses from your taxable income. These can include travel and transport, uniforms, office running costs such as stationery or phone bills, and the cost of business premises, whether that's an office or at home. 
• Trading allowance: Alternatively, self-employed filers can choose to use the ‘trading allowance’. This deducts £1,000 from your gross self-employment income. If you use the trading allowance, however, you can’t also deduct actual expenses.
• Charitable giving tax relief: If you’re a higher-rate or additional-rate taxpayer and have made Gift Aid declarations when giving to charity, you can use your tax return to claim back the difference between the basic tax rate and the rate you pay. 
• Tax relief on pension contributions: Contributions to a pension are eligible for tax relief, but how it's claimed will depend on the type of pension you have. If your employer uses a ‘relief at source’ approach, or if you have a personal pension, you will only receive basic-rate tax relief - higher and upper-rate taxpayers have to claim the extra via their tax returns. 
• Capital gains tax (CGT) allowances: If you're declaring capital gains – through selling shares or an investment property, for example – you get an annual allowance before CGT is payable. You can also offset losses from the same or a previous tax year to reduce your bill. Just register the losses on your self-assessment form.
• Dividend tax allowance: If you're a self-employed contractor and choose to pay the bulk of your income in dividends, you won't need to pay any tax on the first £2,000 of dividend income you receive. You may also be able to use your tax-free personal allowance on top.

4. Claim unused allowances from previous years  

The 31 January 2024 deadline is also your chance to amend last year's tax return and claim unused allowances from 2021-22. If you're in a rush and don't have time to do it, remember you can make changes up to four years after the end of the tax year it relates to. 

After Wednesday's deadline, however, any amends relating to tax returns from 2021-22 or earlier will need to be requested by writing to HMRC.

Once you’ve filed your 2022-23 return, you can amend it online anytime from 72 hours after you’ve filed it until 31 January 2025. 

5. Pay your tax bill on time

Be mindful of deadlines, penalties and fines. Unless you have what HMRC considers a ‘reasonable excuse’ - such as the death of a partner or hospital stay - failure to file by 31 January will see you face a penalty fee and incur interest on what’s owed.

Don’t forget the deadline for paying the bill is also the same as filing and if you miss it you’ll be charged interest from the date the payment was due - that’s now set at 7.75%. The longer you leave it, the higher the charges and interest you will incur.

• Find out more: late tax returns and penalties for mistakes

6. Check for mistakes

So, you've completed your form and are ready to file - but before you do, take one last, careful look at all the information to ensure it's accurate and there are no errors.

HMRC can impose fines for mistakes if it thinks you haven't taken 'reasonable care' in filling out the form. Penalties are based on the amount of tax you owe, and whether HMRC believes you have provided incorrect information on purpose.

But don't panic if you suddenly realise you're missing something - it's possible to submit estimates and add that information later. Just make it clear when you submit the form. The important thing is you don't miss the deadline.

7. Use the Which? tax calculator

You can also use the Which? tax calculator to get to grips with your tax liabilities and allowances. 

It provides clear, no-nonsense explanations about the different types of taxable income, plus suggestions for allowances you might have missed. You can even use the tool to file your return directly to HMRC.