How to Prepare for the Self-Assessment Deadline (31 January)
If you’re self-employed, a company director, or have income outside PAYE, you’re likely required to complete a Self-Assessment tax return each year. The deadline to submit your return online and pay any tax owed is 31 January, and preparing early can save you time, stress, and potentially money.
Here’s how to get organised and submit your Self-Assessment on time.
1. Know if You Need to File
You must file a Self-Assessment tax return if, in the previous tax year (6 April to 5 April), you:
- Earned over £1,000 from self-employment
- Received untaxed income (e.g. rental income, dividends, crypto profits)
- Are a partner in a business partnership
- Are a company director (excluding directors with income solely from PAYE)
- Claimed Child Benefit and earned over £50,000
- Earned more than £100,000 in income
If you’re unsure, you can use the HMRC online tool or speak to your accountant to clarify.
2. Register Early (If It’s Your First Time)
If this is your first time filing, you need to register for Self-Assessment with HMRC. This should be done well in advance of the deadline, as HMRC will send you a Unique Taxpayer Reference (UTR) and an activation code for your online account.
It can take up to 10 working days to receive your UTR, so don’t leave this until the last minute.
3. Gather Your Paperwork
You’ll need details of all your income and expenses for the tax year (6 April to 5 April). This may include:
- Invoices and business expenses (for the self-employed)
- P60/P45 forms
- Bank interest statements
- Dividend vouchers
- Rental income and expenses
- Pension contributions
- Gift Aid donations
- Student loan statements
Organise your records early to avoid scrambling at the last moment.
4. Calculate and Pay What You Owe
Once your return is complete, you’ll be told how much Income Tax and National Insurance you owe. You must pay this by 31 January, plus:
- The first ‘payment on account’ for the current tax year (if applicable)
Payment on account is a way of prepaying part of next year’s tax based on your current bill. It does catch people off guard, so be sure to factor this into your budgeting. Ask your accountant if you are unsure.
5. Use Software or an Accountant
You can file your Self-Assessment directly through the HMRC website, but using accounting software or a qualified accountant can make the process smoother and help identify tax-saving opportunities.
An accountant can also help you avoid mistakes, such as claiming ineligible expenses or forgetting to declare income, which could result in fines.
Final Thoughts
The key to stress-free Self-Assessment is preparation. Start early, keep your records organised, and don’t hesitate to ask for professional support if needed. Missing the 31 January deadline can result in automatic penalties—starting at £100 and increasing the longer you delay.
Set a reminder, gather your documents, and take control of your tax responsibilities before the rush begins.
From April 2026, Making Tax Digital comes in to force for those earning over £50,000 a year, and the above preparation will be needed for the new quarterly submission deadlines.
MTD for Income Tax Self Assessment (ITSA) will apply from April 2026 to self-employed individuals and landlords with income over £50,000, and from April 2027 for those earning over £30,000.
📞 Get in touch with GMS Accountants if you need help with your self assessment.
