Self Assessment rarely makes it to the top of anyone’s to-do list. Deadlines creep up, paperwork hides in inboxes and the rules change just enough to cause confusion.
The good news is that with a little planning you can file with confidence, avoid penalties and keep your tax bill accurate.
SeavorChartered has pulled together a practical survival guide below to help you stay on top of Self Assessment for 2025. Whether you are self-employed, have property income or have had other changes to your finances this year, here is what to focus on.
Who needs to file a self assessment?
You normally need to file a Self Assessment return if any of the following apply:
- You were self-employed or in a partnership
- You received untaxed income such as rent, dividends above the allowance, foreign income or capital gains
- You or your partner claimed child benefit and either of you earned over £60,000 (with the charge tapering out completely at £80,000)
For PAYE-only employees, HMRC has removed the income threshold that previously forced high earners to file. If all of your income is taxed at source you may not need to file, but check carefully if you have dividends, property income or other untaxed sources.
Information to gather before starting your self assessment
Keep everything in one folder so nothing gets missed. Useful records include:
- P60s, P45s and benefit statements from employment
- Invoices, expenses and bank statements for self-employment
- Rental accounts, mortgage interest and agent fees for property income
- Bank interest, dividend vouchers and investment statements
- Capital gains paperwork for any assets sold, including crypto
- Pension contributions and Gift Aid donations
- Student loan details where relevant
HMRC can ask for records for up to five years, so hold on to them.
Completing your tax return online
- Check you can sign in with your Government Gateway and have your UTR ready
- Start early. You can file from 6 April and filing early helps spread the cost
- Enter income and reliefs carefully. Pay attention to savings interest, dividends and pension reliefs
- Review payments on account. New filers often have to pay two instalments in January which can feel like two bills at once
- Submit and pay by 31 January. If you cannot pay in full, set up a Time to Pay plan to spread the cost
Penalties and interest
The fixed penalty for missing the deadline is £100.
After three months HMRC can add daily penalties of up to £900, with further charges at six and twelve months.
Late payment penalties are 5% of the tax due at 30 days, six months and twelve months, plus interest currently set at 8%.
Common self assessment pitfalls
We often see people tripped up by:
- Forgetting small amounts of bank interest or dividends
- Using the wrong student loan plan type
- Missing out on higher-rate pension or Gift Aid relief
- Being surprised by payments on account in the first year
- Applying the wrong capital gains rates for disposals across 30 October 2024
Final thoughts
Filing early is the simplest way to stay in control. It gives you time to gather records, claim the reliefs you are entitled to and plan for payments. If you expect your income to fall, consider whether reducing payments on account is sensible. If paying in full will be difficult, set up a Time to Pay arrangement before charges build up.
If you would like a second pair of eyes on your return, help with reliefs or full preparation and filing, we can step in at any stage. Share what has changed for you this year and we will help you file with confidence.
Get in touch with SeavorChartered today for support with your Self Assessment.
