How to fill in a Self Assessment tax return

Yes, if:

• your self-employment income was more than £1,000 (before taking off anything you can claim tax relief on)
• your income from renting out property was more than £2,500 (you’ll need to contact HMRC if it was between £1,000 and £2,500)
• you earned more than £2,500 in untaxed income, for example from tips or commission
• your income from savings or investments was £10,000 or more before tax
• you need to pay Capital Gains Tax on profits from selling things like shares or a second home
• you’re a director of a company (unless it was a non-profit organisation, such as a charity)
• you, or your partner’s, income was over £60,000 and you’re claiming Child Benefit
• you have income from abroad that you need to pay tax on, or you live abroad but have an income in the UK
• your total taxable income was over £150,000
• if you earned over £50,270 in the 2023/24 tax year and make pension contributions you might have to complete an assessment to claim back the extra tax relief you’re owed
• you’re a trustee of a trust or registered pension scheme
• your State Pension was your only source of income and was more than your personal allowance
• you received a P800 from HMRC saying you didn’t pay enough tax last year.

You can also fill in a Self Assessment tax return if you want to make voluntary Class 2 National Insurance contributions. This will help you qualify for benefits such as the State Pension. Since April 2024, if you’re self-employed, you will no longer need to pay Class 2 National Insurance contributions when you complete your taxes, unless your profits are less than £6,725 and you wish to pay voluntarily.

If you’ve never submitted a tax return before, the first step is to register for Self Assessment on GOV.UKOpens in a new window

Depending on how you’re employed, there are different ways to register.  

Check out these step-by-step guides from HMRC to find out how to get started. 

• Self AssessmentOpens in a new window if you’re self-employed  
• Self Assessment if you’re not self-employedOpens in a new window but need to declare an income 

If you’re in a partnership, you will need to complete a SA400 form and register the partnership for Self AssessmentOpens in a new window on GOV.UK.

When you’ve registered, you’ll be sent your Unique Taxpayer Reference (UTR).

If you want to submit your Self Assessment form online, you’ll then need to set up a Government Gateway account. To do this, follow the instructions in the letter containing your UTR.

When you’ve set up the account, you’ll get an activation code in the post. You’ll then need to complete the set-up of your Gateway account.

If you’ve submitted Self Assessment tax returns before, you’ll need your old UTR to register and set up the account.

It’s best to make sure you can access your Gateway account before you try to submit your Self Assessment. This saves time if, for any reason, you can’t log in.

You submit tax returns for tax years, not calendar years. And you do this in arrears.

For example, for the 2023/24 tax year – running 6 April 2023 to 5 April 2024 – you would:

• need to register for Self Assessment by 5 October 2024 if you’ve never submitted a return before
• submit your return by midnight 31 October 2024 if filing a paper tax return
• submit your return by midnight 31 January 2025 if filing online
• pay the tax you owe by midnight 31 January 2025.

If you fail to meet one or more of these deadlines, you might be charged a penalty fee and interest on late payments.

If you’ve never filled in a Self Assessment tax return before, it can look daunting. But when you understand the process, it’s relatively simple – as long as you have all the information you need.

Before you start, make sure you have:

• your ten-digit Unique Taxpayer Reference (UTR)
• your National Insurance number
• details of your untaxed income from the tax year, including income from self-employment, dividends and interest
• records of any expenses relating to self-employment
• any contributions to charity or pensions that might be eligible for tax relief
• P60 or other records showing how much income you received that you’ve already paid tax on.

It’s also a good idea to read the relevant HMRC help sheets, particularly on the extra sections (called supplementary pages) that relate to why you’re filling in the Self Assessment tax return.

If you’re filling in your Self Assessment form online, you can also find help online by clicking the ‘?’ next to the different fields.

There are two sections to a Self Assessment tax return. The main section is the SA100, which deals with:

• taxed and untaxed income in the form of dividends and interest
• pension contributions
• charitable donations
• benefits, including State Pension, Child Benefit and Blind Person’s Allowance.

Do you have income to declare as a company director, a foreign national (or dual resident), from self-employment, property, Capital Gains, or from abroad? If so, you’ll also need to fill in a supplementary page.

You don’t have to fill in the short-form tax return (SA200) because HMRC send it to you.

Before you start filling in the SA100 or the supplementary pages, it’s important to read the help sheets and notes related to the section.

This section is specifically for:

• declaring tax and untaxed income from interest earned from bank and building society accounts, and
• dividends from shares.

If you’re retired, you need to enter the:

• total amount of State Pension you were entitled to receive over the tax year
• gross amount of any State Pension lump sum
• gross amount of any annuities or pension lump sums (other than State Pension).

If you’re claiming benefits, you’ll need to enter the:

• amount received in Incapacity benefit and Jobseeker’s Allowance
• grand total of taxable benefits received – this includes Bereavement Allowance, Carer’s Allowance and Industrial Death Benefit.

You don’t need to include:

• Attendance Allowance
• lump sum Bereavement Support Payment
• Personal Independence Payment (PIP)
• Pension Credit
• Working Tax Credit
• Child Tax Credit
• income-related Employment Support Allowance
• Maternity Allowance, or
• War Widow’s Pension.

These benefits aren’t taxable.

This section is for any other taxable income, not related to interest, dividends or on anything on the supplementary pages.

You can also enter any allowable expenses related to this income, and any income tax you’ve already paid on it.

Any payments into a registered pension scheme, annuity contract, or employer’s scheme where deductions were made after tax.

Grand totals of Gift Aid donations made to charities during the tax year. You should also enter amounts for any shares, securities, land or buildings gifted to charities.

Show whether you’re claiming Blind Person’s Allowance.

Show whether you’re currently repaying your Student Loan and deductions made by your employer.

You only need to fill in this section if you’re receiving Child Benefit and your income was over £60,000.

Complete this section if your income for the tax year was less than the Personal Allowance, and you want to transfer some of your Personal Allowance to your spouse.

Do you have extra income to declare from self-employment, property or capital gains? If so, you’ll need to fill in a supplementary page. If you’re:

• self-employed, it's page SA103
• reporting property income, it's page SA105
• declaring capital gains, it's page SA108.

In these pages, you’ll need to report income from these sources that you haven’t paid tax on.

You should also declare any allowable expenses, which will be deducted from your tax bill.

If you’re earning money through self-employment, you’ll be asked to enter your turnover under the business income section.

This is the grand total of everything you had coming in during the tax year, before expenses are deducted.

If you have more than one source of self-employed income, you can enter this amount separately. But make sure you state as your main employment, the job you earn the most from.

There are two ways to declare your expenses if you’re self-employed.

The different expenses you can include if you’re self-employed are:

• cost of stock bought for resale
• cost of equipment used at work
• wages, salaries and other staff costs
• payments to subcontractors (if you work in the construction industry)
• vehicle and travel expenses
• work building costs (including rent, power and insurance)
• repairs and maintenance for work buildings and vehicles
• office costs (including internet access, phones and stationery)
• advertising and business entertainment costs
• interest on loans
• bank, credit card and other financial charges
• accountancy, legal and other professional costs.

You don’t need to send in proof of your expenses, such as receipts, when you submit your Self Assessment tax return.

You’ll need to keep records of expenses for five years after you submit your return for that tax year in case HMRC ask you to produce them.

If you’re a landlord, you’ll be asked to enter the income from rented properties in two separate sections.

In the first section, you’ll need to enter the total income from all furnished holiday lettings in the UK. If you have any furnished holiday lettings in the European Economic Area, you’ll need to enter the total income from these on a separate page.

In the second section, enter the total rent and income from other properties.

Income you need to declare for Capital Gains Tax is called ‘disposal proceeds’.

You’ll need to fill in a separate ‘disposal proceeds’ total for:

• residential property
• non-residential property, and
• shares and securities.

On a Capital Gains Tax return, you can claim for ‘allowable costs’. These include:

• the price paid to buy the asset in the first place
• costs of any improvements (must be reflected in the asset when it’s sold*)
• other costs in buying or selling the asset – such as Stamp Duty when buying a property.

*This means, the improvement still needs to be present when the asset is sold. For example, you can’t claim for a new carpet in a house if you remove the carpet before you sell the property.

It’s important to keep good records to make sure you don’t claim for the same thing twice. This is because you might be claiming expenses as part of your Self Assessment tax return for property in previous years.

For example, if you claimed for maintenance on a buy to let property in a previous tax year, you can’t claim for the same expense as part of your Capital Gains tax return when you sell the property.

When you’ve submitted your Self Assessment tax return, you’ll be told how much tax and — if you’re self-employed — National Insurance contributions you’ll need to pay.

The deadline for payment is 31 January.

Yes, you can make payments in instalments. But these are an advance on your next tax bill.

You can arrange for what’s called a budget payment plan through your online account and decide how much you want to pay each week or month. You can also choose to stop paying for up to six months.

The only restriction is that you must be up-to-date with your previous Self Assessment payments.

But you can’t use this to pay for a previous tax bill in instalments.

There are many ways to pay your Self Assessment tax bill. But the length of time depends on which method you choose.

If you’re making your payment close to the deadline day, choose one of the faster options to make sure you don’t get penalised.

The fastest ways to pay are:

• online or telephone banking
• Clearing House Automated Payment System (CHAPS)
• debit or corporate credit card
• in person at your bank or building society.

But you can arrange for a bank transfer, Direct Debit or send a cheque.

If you miss the deadline to register, submit your return or pay your bill – you’ll get a penalty.

If you’re up to three months late filing or paying tax, there’s a penalty of £100. If it’s later than this, the penalty will be more. You can appeal if you have a reasonable excuse.

You don’t need to fill in your Self Assessment tax return all in one go. So it’s a good idea to start early and take your time to avoid mistakes.

Before you submit it, you’ll be given the chance to check your return and correct any mistakes you’ve made.

If you realise you’ve made a mistake after you’ve submitted, you can still make changes until the filing deadline the year after. This means, for the tax return you submitted by 31 January 2024, you can make changes until 31 January 2025.

Unless your last Self Assessment tax bill was less than £1,000, or you’ve already paid more than 80% of all the tax you owe, you’ll be asked to make ‘payments on account’ towards your next tax bill.

‘Payments on account’ are made up of two payments, each one is half of your previous year’s tax bill. They’re due by 31 January and 31 July.

If you have an outstanding payment, or are worried you might miss a future paymentOpens in a new window call the HMRC Time to Pay helpline on 0300 200 3822.

To use the Time to Pay service, you must have a Self Assessment tax bill of between £32 and £30,000.

You must also have no outstanding tax returns and have no other debts or payments set up with HMRC.

If you’re not eligible under these requirements, you might still qualify for Time to Pay. But you’ll need to contact HMRC direct.

If you can’t afford to pay your tax bill, you need to contact HMRC as soon as possible by calling the Business Payment Support Service on 0300 200 3825. This line is for everyone, not just for businesses.

HRMC will look at:

• how much you owe
• your income
• expenditure
• assets
• savings and investments.

They’ll then decide whether you’ll be given more time to pay.

If you don’t pay on time, it’s likely you’ll have to pay interest and penalty charges.

You might be offered more time to pay or offered the chance to pay in instalments.

Tax is a priority debt. So if you can’t pay, or are struggling to pay, your tax bill – you need to call the Business Payment Support Service on 0300 200 3835.

If you don’t and simply refuse to pay, HMRC will take enforcement action against you. This can include directly collecting what you owe through:

• your earnings
• your bank account
• your pension, or
• repossession, or a debt collection agency.

You could also be faced with court action, risk being made bankrupt or having your business closed down.