9 Simple Ways To Do A Self Assessment in 2025

Alan Bermingham

10 Years of Expertise in Fintech Innovation

6 min read

How to do a Self Assessment outlines the essential step-by-step procedure required by His Majesty’s Revenue and Customs for self-employed individuals, landlords, and high earners in the UK. The process begins with registering for Self Assessment to obtain a 10-digit Unique Taxpayer Reference (UTR) number, followed by setting up an online government gateway account. Taxpayers must compile complete financial records for the tax year (6 April to 5 April), including self-employment income, allowable business expenses, rental earnings, and dividend payments. Online tax returns must be completed and submitted alongside full tax payments by 31 January following the end of the tax year to avoid an automatic £100 late-filing penalty. Utilising Open Banking tax applications like Pie streamlines the process by auto-categorising expenses, calculating tax liabilities in real time, and submitting compliant returns directly to HMRC.

Lets Not Beat Round The Bush...

Ready to tackle your Self Assessment but not sure where to start?

Filing your tax return doesn’t have to be a headache! With a few easy steps, you can get organised, maximise deductions, and stay on top of deadlines.

Let’s dive into some tips to make this tax season a breeze!

Gather Your Income Records Early

One of the best ways to make Self Assessment a breeze is to gather all your income records early. Trust us—it’s a lifesaver.

From salary slips to freelance invoices and rental income statements, keeping everything organised throughout the year means you won’t be frantically searching for paperwork at the last minute.

Having all your documents ready and organised makes it so much easier to complete your tax return quickly and accurately.

Plus, it helps you avoid mistakes that could delay your tax refund or lead to extra back-and-forth with HMRC.

Whether it’s a digital folder on your computer or a simple filing system at home, having your income sorted out and ready to go means you’re prepared for a smooth Self Assessment process when the time comes! If you ever reach a point where you need to close your account, we also provide clear instructions for managing your data privacy and deleting your account within the app settings.

2. Keep Track of Your Expenses

Keeping track of expenses throughout the year is a game-changer when it’s time to file a tax return.

For our self-employed clients, every little expense—from office supplies to travel costs—really adds up. By keeping these records organised, you can maximise tax relief and reduce what you owe come tax season.

Using an online account or a reliable expense-tracking app makes this easy, and many of our clients find it helpful to add in things like pension contributions and regularly check their bank statements.

This way, you're not scrambling for paperwork and receipts at the last minute; instead, everything is ready to go.

Whether you’re filing online or with a paper form, organised expense records save you both time and stress, and they can even increase your tax savings.

A bit of effort each month means a lot less worry when it’s finally time to submit your return!

3. Understand the Self Assessment Deadlines

Staying on top of Self Assessment deadlines is key to keeping things smooth with HMRC!

There are two main dates to remember: 31 January for online filing and 31 October for submitting a paper return. Missing these deadlines can lead to late filing penalties, which can add up fast, so it’s best to plan ahead.

For those making two payments on account, it’s especially helpful to file on time. Filing early means you’ll have a clear view of any tax you owe, including your first payment in January and the second payment in July.

Plus, filing on time (or early) can help you avoid last-minute stress and gives HMRC time to process any dividends received or additional income, especially for limited companies.

If you’re new to Self Assessment, you may need an activation code to set up your online account, so be sure to contact HMRC well before the deadline if you need any support.

4. Register for Self Assessment if You Haven’t Already

If you’re earning self-employed income, receiving rental income, or have any untaxed income, it’s crucial to register for Self Assessment with HMRC.

This process gets you set up with a Unique Taxpayer Reference (UTR), which you’ll need whenever you file a tax return. Registering is simple, but it’s best not to leave it until the last minute, as delays can lead to missed deadlines and potential penalties.

To register, head to the HMRC website and follow the steps to create an account. You’ll need some personal details and may need to wait a few days for your activation code to arrive by post.

Once you’ve activated your account, your UTR will be issued, giving you access to all the online services you need to manage your Self Assessment.

Registering early helps you avoid a mad dash in January and ensures you have everything ready for a smooth filing experience.

Plus, it keeps you on track with HMRC from the start, giving you peace of mind throughout the tax year!

5. Use HMRC’s Online Services or App

We’ve seen firsthand how helpful HMRC’s online services and app can be for managing Self Assessment tax!

Clients who use the online account find it so much easier to keep track of their tax return—everything is right there, whether it’s for the current tax year or a previous tax year. It’s a huge timesaver compared to sorting through piles of paper.

One of the best features of the app is the ease of handling self assessment payments and knowing exactly how much tax you owe.

You can make tax payments directly, set up reminders, and stay on top of your tax bill without any extra fuss. For those who might have missed a paper tax return or needed to double-check a payment, the online service has been a game-changer.

With the digital tools, clients feel much more organised, knowing they have everything in one place and can log in anytime to check their status.

So, if you’re aiming for a smoother Self Assessment experience, give HMRC’s online services or app a try! It’s like having your own tax hub right at your fingertips.

6. Double-Check Your Information Before Submitting

One thing we always remind clients at Pie Tax is to double-check everything before hitting “submit” on your Self Assessment return.

It might seem obvious, but simple mistakes—like an incorrect tax code or missing national insurance number—are some of the biggest culprits when it comes to delays. Taking an extra few minutes to review can save you a lot of hassle later.

Accuracy is key, especially when entering details on your income and expenses. Even minor errors can mean your assessment return needs additional checks, which can delay things and even lead to extra charges if you have to pay interest.

Make sure your account details are correct too; an incorrect bank account number could cause issues with refunds or payments.

So, before you file your tax return online, take a little extra time to go over everything. It’s a small step that goes a long way in avoiding any last-minute stress, and ensuring accuracy now makes it much easier to request your SA302 tax calculation document from HMRC later if you need proof of income for a mortgage or loan application.

7. Consider Setting Up a Direct Debit for Payments

Setting up a Direct Debit for your Self Assessment payments can make life so much easier!

One of the biggest perks is that it ensures your payments are made on time automatically, helping you avoid late fees or penalties from HMRC. For clients who prefer a “set it and forget it” approach, Direct Debit has been a lifesaver.

To get started, log in to your HMRC online account and follow the steps to set up Direct Debit. You’ll need your bank details on hand, and once it’s set, HMRC will deduct the payment on the due date.

It’s that simple! Plus, you can always check the payment status in your account.

Using Direct Debit is also a great way to manage your cash flow. You won’t have to worry about scrambling for funds at the last minute or missing important payment deadlines.

Instead, everything is set up in advance, keeping your tax payments smooth and stress-free! To be fully prepared, ensure you understand exactly when to pay your self-employed tax so that your Direct Debit mandate covers the correct amounts at the appropriate times of the year.

8. Use HMRC’s Self Assessment Tools for Help

Many of our clients find HMRC’s Self Assessment tools incredibly useful for simplifying their returns.

From guidance on income and expenses to understanding tax codes and allowances, these tools help make sure nothing’s missed.

The calculators, in particular, offer a quick way to estimate what you might owe and help you avoid errors when handling tax calculations.

If your situation is more complex—like managing self-employed income, dividends, or even capital gains—consulting a tax adviser can be a smart move.

For many, combining HMRC’s tools with a tax adviser’s help makes filing a breeze and keeps stress at bay!

9. Review and Save Your Submission Confirmation

Once you’ve finished filing your Self Assessment tax return, make sure to review all the details and save your submission confirmation.

Completing a Self Assessment involves several steps: gathering income records, calculating income tax owed, and accurately filling out the assessment tax return. After submitting, that confirmation from HMRC is your proof that everything went through smoothly.

We always advise our clients to keep a digital or printed copy of this confirmation, whether it’s saved in a secure folder or filed with your tax documents.

Having this proof of submission can save you from future issues—especially if there’s ever a question about your tax return status or the income tax you paid.

By taking a moment to review and save your confirmation, you’re ensuring peace of mind for the year ahead!

Final Thoughts

And there you have it—a straightforward roadmap to tackling your Self Assessment with confidence!

Filing your tax return doesn’t have to be stressful or overwhelming if you stay organised and follow a few simple steps.

From gathering your income records and tracking expenses to setting up a Direct Debit and using HMRC’s tools, a little prep can go a long way in making the process smooth.

Just remember to keep an eye on deadlines, double-check everything before you submit, and save that all-important submission confirmation. It’s all about keeping things simple and avoiding last-minute rushes.

And hey, if you’re ever unsure, don’t hesitate to get a bit of expert advice—it’s worth it for peace of mind.

With everything in place, you’ll be all set to file and get back to what really matters. Here’s to a stress-free tax season!