How to Make Self Assessment Easier

The easiest way to make Self Assessment less stressful is to start early.

For the 2025/26 tax year, which ran from 6 April 2025 to 5 April 2026, the main online filing and payment deadline is 31 January 2027.

You can complete your return yourself or ask an accountant to prepare and submit it for you. Whichever route you choose, getting organised early can make the process considerably easier.

In this article, we explain how to make Self Assessment easier, including the documents you need, the key deadlines, common mistakes to avoid and the steps you can take to prepare and file your tax return with less stress.

Because Self Assessment can be complicated and time-consuming, professional support can make the process much easier. Addition combines a simple digital process with support from an experienced accountant who prepares your return for you, helping you file accurately and with less hassle.

See how Addition's Self Assessment service works.

Self Assessment checklist

If you want to make your Self Assessment easier, work through these steps:

Check whether you need to submit a Self Assessment return.
Check that you are registered with HMRC. If you need to register or reactivate your account and have missed the 5 October 2026 deadline, do it as soon as possible.
Check whether Making Tax Digital for Income Tax applies to you.
Gather your income, expense and tax records.
Check your income against your records and supporting documents.
Review your expenses and any tax reliefs you may be entitled to claim.
Check your tax calculation, including any payments on account.
Review the return, submit it and save your confirmation and records.

Doing these things well before the filing deadline can turn Self Assessment from a January rush into a much more manageable task.

What is Self Assessment?

Self Assessment is the system HM Revenue and Customs (HMRC) uses to collect Income Tax from people whose tax is not fully collected automatically, such as through PAYE.

It helps to separate Self Assessment into three different tasks:

Registering tells HMRC that you need to complete a tax return.
Filing reports your relevant income, gains, expenses and tax reliefs.
Paying settles the tax you owe.

These are separate responsibilities. Registering does not mean you have filed your return, and filing does not necessarily mean you have paid the resulting tax bill.

Do I need to complete a Self Assessment tax return?

You must submit a tax return if HMRC has asked you to send one, unless HMRC subsequently agrees that you no longer need to.

For the 2025/26 tax year, you will also normally need to complete a return if you were self-employed as a sole trader and earned more than £1,000 before deducting expenses, or if you were a partner in a business partnership.

Other circumstances can also mean you need to file. For example, a return may be required if you have Capital Gains Tax to pay or receive certain types of untaxed income.

This could include income from:

Renting out property or land
Tips and commission
Savings and investments
Dividends
Foreign income
Taxable UK income if you are a non-UK resident

The rules depend on your circumstances, so do not assume that you need (or do not need) a return based on one source of income alone.

If you are uncertain, use HMRC's online Self Assessment checker.

If HMRC has already asked you to submit a return but you believe you no longer need to, tell HMRC rather than simply deciding not to file.

What are the Self Assessment deadlines for 2025/26?

For the 2025/26 tax year, the key dates are:

5 October 2026: Deadline to tell HMRC if you need to complete a return and have not sent one before, or if you previously registered but did not need to send a return for 2024/25.
31 October 2026: Deadline for HMRC to receive a paper tax return.
30 December 2026: Deadline for submitting an online return if you want HMRC to collect an eligible Self Assessment bill through your PAYE tax code.
31 January 2027: Deadline for submitting an online tax return and paying the tax due.
31 July 2027: Deadline for the second payment on account, where applicable.

What if you miss the 5 October registration deadline?

If you need to register for Self Assessment and have not done so by 5 October 2026, register with HMRC as soon as possible.

HMRC says you could receive a penalty if you tell them after 5 October.

If you register after the deadline, HMRC will send you a letter or email giving you a different deadline for submitting your return. This will normally be three months from the date of that letter or email.

However, this does not automatically extend the deadline for paying your tax. Tax due for 2025/26 must still normally be paid by 11:59pm on 31 January 2027.

Does filing Self Assessment early mean paying tax early?

No. You can submit your tax return before the deadline without having to pay the tax immediately.

Filing early can make Self Assessment easier because you know what you owe sooner. This gives you more time to budget for the bill and resolve any questions before payment is due.

What documents do I need for Self Assessment?

Having the right information ready before you begin is one of the simplest ways to make Self Assessment easier.

The exact documents you need depend on how you earned your income and your circumstances, but your checklist could include:

Your Unique Taxpayer Reference (UTR)
Your National Insurance number
P60, P45 and P11D forms, where relevant
Bank statements
Records of savings interest and other untaxed income
Sales invoices and self-employed income records
Receipts and records for business expenses
Rental income and property expense records
Dividend vouchers and investment statements
Records relating to capital gains
Pension contribution records
Gift Aid records
Details of foreign income
Details of other taxable income

You do not normally send all of your supporting records to HMRC with the return. However, you need sufficient records to complete it accurately, and HMRC can ask to inspect them.

If you are self-employed, HMRC generally requires you to keep your business records for at least five years after the 31 January submission deadline for the relevant tax year.

How to make Self Assessment easier in eight steps

1. Check whether you actually need to file

Start by establishing whether Self Assessment applies to you and which tax year you need to report.

HMRC provides an online checker if you are uncertain.

If HMRC has already asked you to file but you believe you no longer need to, contact HMRC. Do not simply ignore the request because you believe you have no tax to pay.

2. Check your Self Assessment registration

If this is your first Self Assessment, you may need to register with HMRC.

Once registered, you will receive a Unique Taxpayer Reference, usually called a UTR. This identifies your Self Assessment record.

If you have used Self Assessment before but did not need to send a return for the previous tax year, you may need to reactivate your account.

For 2025/26, the relevant deadline to tell HMRC is 5 October 2026. If you have missed that date, register as soon as possible rather than leaving the problem until January.

3. Check whether Making Tax Digital applies to you

Making Tax Digital for Income Tax started on 6 April 2026 for some sole traders and landlords.

If your total qualifying income from self-employment and property was more than £50,000 in the 2024/25 tax year, you should generally already be using Making Tax Digital for Income Tax for 2026/27.

The threshold is then being extended. If your qualifying income was more than £30,000 in 2025/26, you will generally need to start using Making Tax Digital for Income Tax from 6 April 2027.

Qualifying income is broadly the total gross income you receive from self-employment and property before expenses. Other income, such as employment income, does not count towards this particular threshold.

If Making Tax Digital applies to you, you need compatible software to keep digital records and send the required information to HMRC.

Starting Making Tax Digital for 2026/27 does not remove your responsibility to complete your 2025/26 Self Assessment return. If you need to file for 2025/26, the normal online deadline remains 31 January 2027.

4. Keep all your Self Assessment information in one place

Scattered records can make a relatively straightforward tax return feel complicated.

Instead of keeping some receipts in your inbox, others on your phone and income records in several different folders, create one reliable place for everything relating to your return.

Depending on how you work, that might be accounting software, a secure app or an organised digital filing system.

Useful categories could include:

Employment
Self-employment
Property
Investments
Expenses
Pension contributions
Gift Aid
Capital gains
Foreign income

Good organisation also makes it much easier to identify something that is missing.

5. Reconcile your income before entering figures

Do not rely solely on memory or one set of records.

Compare your income records with supporting information such as:

Bank deposits
Sales invoices
Payment platform statements
Employment documents
Rental statements
Investment records

This can help you identify income that might otherwise be missed and avoid accidentally recording the same amount twice.

If you run a business, keeping your records up to date throughout the year can make this part of Self Assessment considerably easier.

6. Check expenses and tax reliefs carefully

Not every expense is automatically allowable for tax simply because you paid it from a business bank account.

Its tax treatment depends on what the expense was for and the rules that apply to your circumstances.

Keep supporting evidence for costs you intend to claim and be particularly careful where an expense has both business and personal use.

It is also worth reviewing relevant tax reliefs rather than concentrating only on expenses. Depending on your circumstances, information about pension contributions, charitable giving and other reliefs may affect your tax calculation.

If you are uncertain about the treatment of a significant expense or relief, professional advice can be more sensible than guessing.

7. Understand your tax calculation and payments on account

One of the biggest Self Assessment surprises can happen after the return itself has been completed.

Your January payment may include more than the remaining tax for the year that has just ended.

If payments on account apply to you, HMRC asks you to make advance payments towards your next Self Assessment bill.

There are normally two payments on account, due on 31 January and 31 July. Each payment is usually half of the relevant amount from the previous year's bill.

You will not normally have to make payments on account if:

Your relevant previous year's tax was less than £1,000, or
More than 80% of the tax you owed was collected outside Self Assessment

Payments on account do not include amounts such as Capital Gains Tax, so your individual calculation may differ.

Why can a first Self Assessment payment be higher than expected?

Imagine your relevant Self Assessment bill is £3,000 and payments on account apply.

Your January payment could include:

£3,000 for the tax year just completed
£1,500 as your first payment on account towards the following year

That could make your January payment £4,500.

A second £1,500 payment on account would then normally be due by 31 July.

This does not mean you are being charged twice for the same year's income. The additional amount is an advance payment towards your next bill.

Knowing about payments on account before you submit your return can make it much easier to plan your cash flow.

8. Review everything before you submit

Do not treat reaching the final screen as the end of the process.

Review your income, expenses, reliefs and tax calculation before approving the return.

Check that:

All relevant sources of income have been included
The figures match your supporting records
Expenses and reliefs have been treated correctly
Your personal information is accurate
You understand the amount HMRC says you owe
You understand whether payments on account apply

Once your return has been submitted, save your submission confirmation, tax calculation and relevant supporting records somewhere secure.

Making this a habit will also make next year's return easier.

What are the most common Self Assessment mistakes?

Many Self Assessment problems come down to organisation and timing rather than complicated tax rules.

Common mistakes include:

Missing the registration deadline and then continuing to delay
Confusing the registration deadline with the filing deadline
Leaving registration or account access problems until January
Discovering too late that a UTR or document is missing
Forgetting a small or irregular source of income
Entering the same income twice
Claiming an expense without checking whether it is allowable
Failing to keep evidence for expenses
Forgetting about payments on account
Looking only at the balancing payment rather than the total due
Submitting without reviewing the final tax calculation
Failing to save the submission confirmation

Starting earlier gives you time to resolve these problems rather than discovering them days before the deadline.

Should I do my Self Assessment myself or use an accountant?

You can complete your Self Assessment yourself, but that means taking responsibility for gathering the right information, understanding what needs to be declared, checking which expenses and reliefs apply, completing the return and reviewing the tax calculation before submitting it.

Using an accountant can take much of that work off your hands. This can be particularly useful if you have several sources of income, property income, investments, capital gains or expenses you are unsure how to treat. It can also give you reassurance that an experienced professional has reviewed your information before the return is filed.

Addition combines professional accounting support with the convenience of an app. Instead of preparing the return yourself, you answer a few questions and securely upload your documents. A UK-based Addition accountant reviews your information, prepares your Self Assessment and calculates your tax position.

You can then review the completed return and approve it in the app before Addition submits it to HMRC.

This means you get the convenience of managing your Self Assessment digitally without being left to work through the tax return on your own.

Can an accountant submit my Self Assessment for me?

Yes. An authorised accountant or tax agent can prepare and submit your Self Assessment return on your behalf.

You will still need to provide the information required to prepare the return and approve the final figures.

Using an accountant can reduce the administrative burden, particularly if your records are spread across several sources or you are unsure how particular income, expenses or reliefs should be treated.

Can an app make Self Assessment easier?

Yes. An app can make Self Assessment easier when it replaces scattered emails, spreadsheets, photographs of receipts and disconnected conversations with one organised process.

A useful service might allow you to:

Answer questions about your tax circumstances
Upload supporting documents securely
See what information is still outstanding
Track progress
Review your completed return
See your tax position
Approve the return for submission

There is also an important difference between software that leaves you to interpret tax rules yourself and a service that combines technology with professional accounting support.

How Addition makes Self Assessment simpler

With Addition, you answer a few questions and securely upload the documents needed for your return through the app.

An Addition accountant reviews your information and prepares the return. Once it is ready, you can see the completed return and your tax position before approving it in the app.

Addition then submits the approved return to HMRC.

For a standard return, the service costs £119 as a one-off payment. If your tax affairs require additional work, Addition will discuss this with you before proceeding.

See how Addition's Self Assessment service works.

Frequently asked questions about Self Assessment

How can I make my Self Assessment easier?

Start before the filing deadline, check that you need to file and gather all of your records in one place. Reconcile your income, review expenses and reliefs, understand whether payments on account apply and check the completed return before submitting it.

If you do not want to prepare the return yourself, an accountant can handle much of the process for you.

When is the Self Assessment deadline for 2025/26?

The deadline for submitting an online Self Assessment return for the 2025/26 tax year is 31 January 2027. Tax due through Self Assessment is also normally payable by this date.

The paper filing deadline is 31 October 2026.

What should I do if I missed the Self Assessment registration deadline?

If you needed to tell HMRC that you must complete a 2025/26 Self Assessment return and missed the 5 October 2026 deadline, register as soon as possible.

HMRC says you could receive a penalty for telling them late. HMRC will normally give you a filing deadline of three months from the date of its letter or email if you register after 5 October.

However, your tax will still normally need to be paid by 31 January 2027.

Do I need a UTR if an accountant files my tax return?

Normally, yes. Your Unique Taxpayer Reference identifies your Self Assessment record.

If this is your first return and you do not already have a UTR, follow HMRC's registration process.

Can I file my Self Assessment before January?

Yes. You do not need to wait until January to submit your 2025/26 tax return.

Filing earlier gives you more time to understand your tax bill, budget for payment and resolve any problems.

Will filing early mean I have to pay early?

No. Filing your return early does not bring forward the normal payment deadline.

For the 2025/26 tax year, the main payment deadline remains 31 January 2027.

What are payments on account?

Payments on account are advance payments towards your next Self Assessment tax bill.

They are normally paid in two instalments, on 31 January and 31 July. Each payment is usually half of the relevant amount from the previous year's bill.

They do not apply to everyone.

Does Making Tax Digital replace Self Assessment?

Not immediately.

Making Tax Digital for Income Tax has introduced new digital record-keeping and reporting requirements for qualifying sole traders and landlords, beginning with those over the relevant income threshold from 6 April 2026.

If you started using Making Tax Digital in April 2026, you may still need to submit your normal 2025/26 Self Assessment return by 31 January 2027.

How long should I keep my Self Assessment records?

If you are self-employed, HMRC says you must generally keep your records for at least five years after the 31 January submission deadline for the relevant tax year.

Different record-keeping requirements can apply in other circumstances, so check the rules relevant to you.

Is Addition's £119 price suitable for every Self Assessment return?

The £119 one-off price applies to returns within Addition's standard service scope.

If your circumstances mean additional work is required, Addition will explain this before proceeding.

Make your 2025/26 Self Assessment simpler

Self Assessment becomes much easier when you break it into manageable tasks: establish whether you need to file, check your registration, organise your records, review your figures, understand your tax calculation and submit everything before the deadline.

If you still need to register for 2025/26 and have missed the 5 October deadline, deal with it as soon as possible rather than waiting until January.

For everyone else, getting the return started now gives you more time to find missing information, understand payments on account and prepare financially for what you owe.

If you would rather have professional support, Addition combines a digital process with a UK-based accountant who prepares your return for you.

See how Addition's Self Assessment service works.

This article provides general information and does not constitute personal tax advice. Tax requirements, allowable expenses and reliefs depend on individual circumstances. HMRC rules and deadlines can change, so check current HMRC guidance and Addition's current service scope and pricing before acting.

‍