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Posted January 9, 2026

Self Assessment Deadline Approaching: Final Preparations

The 31st January Self-Assessment deadline is just a couple of weeks away. If you haven’t filed yet, now’s the time to get your return sorted. Here are our quick tips to help you cross the finish line without the last-minute panic.

Your Essential Checklist

Gather your documents now. You’ll need your P60 or P45, details of any other income (self-employment, rental, dividends, interest), and records of allowable expenses. Don’t forget pension contributions and charitable donations-these could reduce your tax bill.

Check you’re claiming everything. The Personal Allowance, Marriage Allowance, and trading allowances could all apply to you. Self-employed? Make sure you’re claiming legitimate expenses like home office costs, mileage, and equipment. These small claims add up.

Double-check your figures. A simple typo can trigger an HMRC enquiry. Take five minutes to verify that income matches your records and expenses are in the right boxes. If you’re claiming mileage, confirm you’re using the correct rates.

Don’t Forget Payment on Account

If your tax bill is over £1,000, you’ll likely owe a payment on account for next year too-that’s half your estimated 2025/26 tax bill due on 31st January alongside your 2024/25 balance. Many people forget this, so check your calculation carefully.

The Penalty Clock Is Ticking

Late filing means an automatic £100 penalty, even if you’re just one day late. After three months, daily £10 penalties kick in. Late payment also attracts interest from 1st February. Don’t risk it-file early and pay on time.

Can’t Pay in Full?

If your tax bill is higher than expected and you’re struggling to pay, contact HMRC before the deadline. They may offer a Time to Pay arrangement, but it’s far easier to set up if you ask before 31st January rather than after.

Common Last-Minute Mistakes to Avoid

  • Forgetting to declare gig economy or freelance income
  • Missing rental income or incorrectly calculating property expenses
  • Not declaring foreign income or capital gains
  • Rushing and entering figures in the wrong boxes
  • Leaving it so late that system issues prevent filing

Why File Early?

HMRC’s systems are inundated with returns in the final days before the deadline. Technical glitches happen. Why add that stress? Once you have your information ready, file straightaway. You’ll know exactly what you owe and have time to sort payment.

Need a Hand?

If you’re feeling overwhelmed, uncertain about what to claim, or just want peace of mind that everything’s correct, professional help is available. We can review your situation, optimise your return, and ensure you’re not paying a penny more than necessary.

Running out of time? We still have capacity to help with last-minute Self Assessment returns, but you need to act now. Get in touch today and let us take the stress out of the deadline-contact us for a quick consultation.