Self Assessment Tax Return

How Soon Should I File My Self-Assessment for 2025/26

HMRC opens self assessment filing from 6 April each year, with paper returns due by 31 October and online returns by 31 January following the end of the tax year. Filing early lets you know your tax bill sooner, budget for payments on account, receive any refund faster and avoid the £100 late-filing penalty. New taxpayers must register by 5 October after the tax year they first need to file.

By Jordan Macey MAAT Reviewed by Noor Fiaz Updated 16 Apr 2026 9

Key takeaways

The online self assessment deadline is 31 January following the end of the tax year, while paper returns must reach HMRC by 31 October.
New taxpayers must register for self assessment by 5 October after the end of the tax year in which they first need to file a return.
HMRC charges a £100 penalty the day after the deadline, rising by £10 per day after three months, up to a further £900.
Filing early does not change the payment date. Tax owed and any first payment on account are still due by 31 January.
Payments on account apply when the previous year's bill exceeds £1,000 and less than 80% was collected at source, split across 31 January and 31 July.

Why Filing Your Tax Returns Early Matters

Self Assessment is the system that HMRC uses to collect Income Tax from individuals whose earnings aren’t automatically taxed at source. If you’re self-employed, a sole trader, a company director, or someone who earns extra income - like from rental properties, investments, or freelance gigs—you’ll likely need to file a Self Assessment tax return every year.

Mark your calendars! The deadline to submit your online Self Assessment for the 2025/26 tax year is 31 January 2027. You’ll also need to pay any tax you owe by that date.

While January might feel like it’s ages away, filing your Self Assessment early can really help you dodge a lot of stress. More and more people are opting to file their tax returns well ahead of the deadline, and it’s easy to see why.

So, how soon should you submit your Self-Assessment Tax Return? The simple answer: the sooner, the better! Filing early helps you stay in control, reduces last-minute pressure, and increases your chances of receiving any tax refunds sooner. In this article, we’ll dive into why filing your Self Assessment early for 2025/256 is a smart choice and 2024/25 self-assessment tax return deadlines.

Key Self-Assessment Tax Return Deadlines for 2024/25

HMRC has set deadlines for registration, paper and online submissions, and tax payments. Missing these dates can lead to penalties, so it’s best to stay ahead of the schedule.

Self Assessment Registration Deadline – Who Needs to Register and By When?

If you are filing a Self-Assessment Tax Return for the first time, you should register for Self Assessment. This applies to:

Self-employed individuals earning more than £1,000 in a tax year.
Company directors who receive income outside of PAYE.
Landlords earning rental income.
Those receiving untaxed income, such as dividends, foreign income, or side earnings.

Registration Deadline - 5th October 2026

If you are new to Self-Assessment, you must register by 5th October 2025 for the 2025/26 tax year. Once registered, HMRC will provide you with a Unique Taxpayer Reference (UTR) and instructions on how to file your return.

Self Assessment Tax Filing and Payment Deadlines

The deadlines for your self-assessment tax return for the 2025/26 tax year are as follows:

Paper Tax Return Deadline - 31st October 2026

if you prefer to submit your tax return by post, you must submit your Self Assessment tax return by Midnight, 31st October 2026. Paper submissions take longer to process and thus, HMRC encourages online filing.

Online Tax Return Deadline – 31st January 2026

if you submit online, you must submit your tax return by Midnight, 31st January 2026.

Watch the video below from HMRC to find out more about completing your first tax return:

Payments on Account

When completing your self-assessment tax return, it's essential to consider "payments on account." This system allows you to make advance payments toward your tax bill for the following year. Here's what you need to know:

1. First Payment on Account: If your tax bill exceeds £1,000, you must make an initial payment on account by January 31st, 2026, along with any outstanding tax from the previous tax year.

2. Second Payment on Account: The second payment is due by July 31st, 2027, and represents another advance payment toward your 2025/26 tax year tax bill.

Collecting the Required Information

Before completing your self-assessment tax return, you must gather several key pieces of information. These include:

Income Information: Ensure you have accurate records of all your income sources, including invoices, bank statements, and receipts.
Expenses Documentation: Keep track of your business expenses, such as receipts for office supplies, travel expenses, and equipment purchases. This information will help you claim allowable deductions and reduce your taxable income.
Updating Accounting Software: If you use accounting software like FreeAgent, update it with all your financial transactions and ensure that your data is accurate and current.
P60: If you are employed and receive income through PAYE, you will need your P60 form, which provides details of your salary and taxes paid during the tax year.

Finalising Your Tax Return and Making Payments

Once you have gathered all the necessary information and completed your self-assessment tax return, reviewing it carefully for accuracy is essential. Double-check your income, expenses, and any claimed deductions. After finalising your return, your accountant can help you calculate your tax liability.

Payments for the 2025/26 tax year, including any outstanding tax from the previous tax year and payments on account, are due by January 31st, 2027.

Benefits of Filing Your Tax Return Early

Filing your Self-Assessment Tax Return early comes with several benefits. Many people wait until the deadline, which can lead to last-minute stress, mistakes, and even penalties. Submitting your return ahead of time gives you more control over your finances and allows you to deal with any issues before they become problems.

1. Faster Tax Refunds

One of the top reasons to file your Self Assessment early is to get any tax refund you might be owed sooner. HMRC usually processes early returns more quickly since there are fewer people submitting them at that time.

If you've overpaid on your taxes, you could see that refund credited in your bank account long before the peak season kicks in. That means some extra cash in your pocket just when you could use it!

2. Avoiding Last-Minute Stress

Leaving your tax return until the last minute can really ramp up the stress. You might end up rushing to gather receipts, invoices, and other important documents — and that’s when mistakes tend to happen. Filing early gives you more time to:

Collect all required documents, such as income statements and expense receipts.
Double-check your figures to reduce the risk of errors.
Get help from an accountant if needed, without rushing.

Submitting early also means avoiding delays caused by high demand on HMRC’s online system, which tends to slow down as the deadline approaches.

3. Avoid Penalties

Missing the Self Assessment deadline can really hit your wallet hard. Even if you are just one day late, HMRC will charge a £100 penalty. The longer you delay, the higher the penalties. And if you wait too long, those fines and interest can really add up.

By filing early, you can avoid the stress of late fees and any last-minute hiccups that might prevent you from getting your submission in on time.

4. Time to Plan for Your Tax Bill

Filing your taxes early lets you know exactly what you owe well ahead of time. This gives you more time to:

Plan for your tax payment and avoid cash flow issues.
Budget for any upcoming expenses.
Spread out payments if your tax bill is higher than expected.

For those making payments on account, knowing your tax liability early can help you prepare for upcoming instalments.

This helps avoid the stress of arranging the full amount just before the deadline.

5. Potential for Lower Accountant Fees During Non-Peak Times

‍Accountants for self-employed are really in demand as we approach the January deadline. A lot of them are already fully booked and might not have the capacity to take on new clients during that busy period.

If you file your return early, you’ll have a better chance of getting assistance from an accountant. They’ll have more time to review your return, provide guidance, and ensure everything is in tip-top shape — all without the chaos of the January rush.

6. Helpful for Mortgage or Loan Applications

If you're applying for a mortgage, a loan, or even a rental property, you can expect lenders to request your most recent tax return. This document is essential as it verifies your income and aids them in making informed decisions.

By filing your taxes early, you'll have all the current paperwork at your fingertips, making it easy to send whenever needed. This way, you won't have to put your application on hold or risk losing out on a great deal.

7. Get Ahead of HMRC System Overloads

As the 31 January deadline approaches, a lot more taxpayers rush to submit their returns all at once. During this hectic time, HMRC’s online system can get bogged down or even crash.

By filing early, you can avoid these delays and submit your return smoothly, without any pesky technical issues.

When Should You Hire an Accountant for Your Tax Return?

Filing a Self-Assessment Tax Return may be straightforward for some, but there are situations where professional help can make a big difference. An accountant for sole trader not only saves you time but can also help you avoid penalties and identify tax-saving opportunities.

Signs You Need Professional Help

Consider hiring an accountant if:

Your income comes from multiple sources: If you have various income streams, such as rental properties, freelance work, or dividends, an can help you report everything correctly.
You’re self-employed or own a business: Managing business expenses, tax deductions, and VAT can be complicated. Professional guidance simplifies the process.
You’ve experienced a significant financial change: Events like selling assets, inheriting money, or starting a new business can impact your tax obligations.
You’ve received a tax investigation letter: An accountant can help respond to HMRC queries and reduce your stress during audit.
You want to save time: If you prefer to focus on your business or personal life rather than tax paperwork, outsourcing to an accountant is a smart choice.

How GoForma Can Help Streamline the Process

‍GoForma offers expert accounting services tailored to your specific needs. Our team handles everything from gathering the right documents to completing and submitting your tax return. By choosing GoForma, you’ll have peace of mind knowing that your taxes are in good hands.

As a GoForma client, you also get access to FreeAgent accounting software at no additional cost with all packages. This powerful tool helps track expenses, generate invoices, and manage your finances seamlessly. It makes staying on top of your accounts easy, whether you're self-employed or running a small business.

Working with GoForma gives you the best of both - expert support from experienced accountants and free access to cutting-edge accounting software.

If you're looking to sort out your tax return without long-term commitments, why not try our Self Assessment Tax Return service? You'll get expert help, accurate filing, and a stress-free experience — all without tying yourself to an ongoing plan. Book a free consultation today and tick your tax return off your to-do list!

Frequently asked questions

What is the difference between the paper and online self assessment deadlines?

Paper self assessment returns must reach HMRC by 31 October following the end of the tax year. Online returns have a later deadline of 31 January. For the 2025/26 tax year (6 April 2025 to 5 April 2026), the paper deadline is 31 October 2026 and the online deadline is 31 January 2027. HMRC encourages online filing because paper submissions take longer to process.

What are the key dates in the self assessment calendar?

The tax year runs from 6 April to 5 April. HMRC opens online filing from 6 April, so you can submit your return for the previous year straight away. New taxpayers must register by 5 October. Paper returns are due by 31 October. Online returns and any tax owed are due by 31 January. The second payment on account falls on 31 July.

What are the benefits of filing my self assessment early?

Filing early means you know your tax bill months in advance, giving you time to budget or set up a savings plan. HMRC processes refunds faster outside peak season, so overpayments can be credited sooner. You also avoid the January rush when HMRC's online system slows down, and you have time to correct errors or gather missing information before the deadline.

What happens if I miss the 31 January deadline?

HMRC charges a £100 penalty immediately, even if you owe no tax. After three months, a daily penalty of £10 applies for up to 90 days, adding a maximum of £900. Late payment also triggers surcharges: 5% of the tax owed after 30 days, another 5% at six months and a further 5% at 12 months. Interest runs on all outstanding amounts from the due date.

Can I file my self assessment before the tax year ends?

No. You cannot file a return for a tax year that has not yet ended. The 2025/26 tax year closes on 5 April 2026, and HMRC opens online filing from 6 April 2026. You can submit from that date onwards, provided you have all income and expense figures for the full year. Filing on the first available day still gives you until 31 January 2027 to pay.

When must I register for self assessment if I am new?

You must register with HMRC by 5 October following the end of the tax year in which you first need to file. For example, if you became self-employed during the 2025/26 tax year, register by 5 October 2026. Once registered, HMRC issues a Unique Taxpayer Reference (UTR), which you need to log in and file your return. Late registration can delay your ability to file on time.

What counts as a reasonable excuse for missing the deadline?

HMRC accepts genuine situations beyond your control, such as the death of a partner shortly before the deadline, serious illness or hospitalisation, fire, flood, or a service issue on HMRC's own systems. Excuses that do not qualify include not knowing about the deadline, relying on an accountant who filed late, or finding the online system difficult. You must file as soon as the reasonable excuse ends.

What are payments on account and when are they due?

Payments on account are advance payments toward next year's tax bill. They apply when your previous year's bill exceeds £1,000 and less than 80% of the tax was deducted at source. Each payment is half the previous year's bill. The first is due on 31 January alongside any balancing payment, and the second falls on 31 July. You can apply to reduce them if your income drops.