1. Check if You Need to File
Not everyone needs to file a self-assessment. You must complete one if you:
- Are self-employed and earned more than £1,000 in the tax year.
- Are a landlord earning rental income.
- Earn over £100,000 annually.
- Have significant untaxed income, such as from investments or overseas earnings.
Use HMRC’s online tool to check if you need to file.
2. Register Early
If it’s your first time filing a self-assessment, you must register with HMRC. This should be done well in advance as it can take time to receive your Unique Taxpayer Reference (UTR) and activation code. The deadline for registration is 5 October following the end of the tax year.
3. Know the Key Deadlines
Missing deadlines can result in penalties, so be aware of these key dates:
- 5 October – Register for self-assessment (if new).
- 31 October – Deadline for paper returns.
- 31 January – Deadline for online returns and payment of tax owed.
4. Gather Your Documents Early
To file your return accurately, have the following ready:
- P60, P45, or P11D (if employed)
- Invoices and receipts (if self-employed)
- Bank statements
- Pension and savings interest statements
- Details of any dividends, rental income, or foreign income
5. Claim All Allowable Expenses
If you are self-employed, you can reduce your tax bill by claiming expenses, including:
- Office costs (e.g. phone, internet, stationery)
- Travel and mileage
- Professional fees (e.g. accountant costs)
- Business insurance
Ensure you keep accurate records and receipts for at least five years.
6. Use HMRC’s Online Services
Filing your return online is faster, more convenient, and comes with built-in checks to reduce errors. You can also access HMRC’s online tax calculator to estimate your tax liability before submitting.
7. Consider Payments on Account
If your tax bill is over £1,000, HMRC may ask you to make advance payments towards next year’s tax (due on 31 January and 31 July). Be prepared for these payments to avoid unexpected cash flow issues.
8. Watch Out for Common Mistakes
Common errors include:
- Entering incorrect figures
- Forgetting to include all income sources
- Failing to claim eligible expenses
- Missing the deadline and incurring penalties
Review your return thoroughly before submitting to avoid unnecessary fines.
9. Set Money Aside for Your Tax Bill
Avoid last-minute panic by setting aside a portion of your earnings throughout the year. Consider opening a separate savings account for tax payments.
10. Seek Professional Help If Needed
If your tax affairs are complex or you’re unsure about deductions, hiring an accountant or tax adviser can save you time and help minimise your tax bill.
Final Thoughts
Filing your self-assessment doesn’t have to be stressful. By preparing early, keeping good records, and understanding your obligations, you can file your return with confidence and avoid penalties.
If in doubt, don’t hesitate to get in touch.