6 tips to complete your self-assessment on time, every time! 

6 tips to complete your self-assessment on time, every time! 

Filing your Self Assessment doesn’t have to be a last-minute scramble or a source of stress. In this guide, we’ll walk you through six simple yet effective tips that will help you stay on track and avoid unnecessary delays.

According to HMRC, 97% of those registered for self-assessment filed their tax return on time in 2024. But, with over 11.5 million taxpayers required to file, that still means nearly 350,000 missed the deadline! Let’s dive into what you can do to make sure you’re part of the 97% without breaking a sweat.

1. Get to grips with Self Assessment

If you’re new to Self Assessment - or even if you’ve done it before but still feel a bit unsure - taking time to understand how it all works can pay off. A bit of research upfront can save you hours later, help you avoid mistakes, and maybe even uncover ways to make the process faster and less stressful.

Start with HMRC’s official guidance, forms and help sheets, videos and webinars, or even subscribe to the help and support email service. You’ll find plenty of other useful information online too, like our complete guide to Self Assessment below!

Read more: A Complete Guide to Self Assessment

2. Mark those key dates in your calendar

When it comes to tax deadlines, ignorance is never bliss! One of the simplest ways to stay on top of your Self Assessment is to get the key dates in your diary well in advance (and set reminders!)

Key dates

• 5th October – Deadline to register for Self Assessment (if you’re new to it)
• 31st October – Deadline to submit a paper tax return
• 31st January – Deadline to submit an online tax return and pay any tax you owe

If you leave it till the last minute, you’re more likely to make mistakes. And if you file late, you’ll be liable for penalties from HMRC. 

3. Let software do the heavy lifting

Gone are the days of excel spreadsheets and last-minute calculator marathons. There is no shortage of tools out there that will automatically crunch the numbers for you, keeping your records tidy and your totals accurate, so when it’s time to file, you’re not starting from scratch. 

There’s a growing list of HMRC-recognised Self Assessment filing software that lets you complete and submit your return directly through the platform. Many of these options offer handy features like real-time tax estimates, automatic error checks, and helpful prompts to make sure you’re not missing anything important.

4. Track income and expenses as you go

Using software is all well and good, but if you’re not regularly inputting your income and expenses as you go, you’ll still be facing a whole lot of work come January. 

Records you need to keep include:

• All sales and income
• All business expenses (check which expenses are allowed if you’re unsure)
• VAT records (if you’re registered)
• PAYE records (if you employ people)
• Records about any personal income grants, benefits or pension payments

Don’t forget, just logging the information isn’t enough. You also need to keep physical proof of things like receipts, bank statements and invoices for at least five years after the submission deadline for the relevant tax year. This is because HMRC could check your records to see if you’ve been paying the right amount of tax.

Pro tip: Set a ‘money date’ with yourself once per week, where you go through your expenses and invoices to make sure you’re on top of it all.

5. Don’t leave it to the last minute

You don’t have to wait until January to start your tax return. The earlier you start, the more relaxed and organised you’ll feel when it’s time to submit. Plus, getting your return ready early means you'll have plenty of time to review everything carefully, and if you do need to contact HMRC, you’ll be ahead of the queue and won’t have to deal with the stress of last-minute issues.

Sending in your tax return early also means you can find out what you owe and budget accordingly, and set up a payment plan if you don’t think you’ll be able to pay on time. 

6. Ask for help if you need it

If you ever feel stuck or unsure, you’re not alone. HMRC offers a Self Assessment helpline (0300 200 3310) available Monday to Friday from 8am to 6pm, as well as an online chat service. Before speaking with them, make sure your personal details and address are up to date in your tax account to avoid any security hiccups. Also, have your National Insurance number and Unique Taxpayer Reference (UTR) handy to speed things up.

If tackling your Self Assessment feels overwhelming - especially if it’s your first time - consider getting an accountant on board. They can handle everything for you, or at least give your return a once-over to make sure it’s all in order. It might even cost less than you think, and it could save you time, stress, and the risk of costly mistakes.