What Documents Do I Need for My Self Assessment Tax Return? 2025/26 Checklist

Preparing a Self Assessment tax return starts with a practical question: What information do I need to provide?

This checklist explains the documents you may need for your 2025/26 Self Assessment tax return, covering 6 April 2025 to 5 April 2026. Much of the paperwork will already be available from your employer, pension provider, bank or investment platform.

If you’re unsure whether you need to file, read Do I Need to Complete a Self Assessment Tax Return?.

Self Assessment tax return checklist: At a glance

Not everyone needs every document listed below. The information required will depend on your personal circumstances and the income you’ve received during the tax year.

If you’re unsure whether something needs to be included, it’s generally better to mention it to your accountant rather than leave it out.

1. Employment income

If you were employed on 5 April 2026, you’ll usually receive a P60, which summarises your employment income and the tax deducted through PAYE. If you left a job before then, gather the P45 and any final payslips instead.

You may also need:

• P45: If you left a job during the tax year.
• Employment benefits: Details of taxable benefits, such as a company car or private medical insurance, including a P11D where one has been issued. Some benefits are taxed through payroll instead.
• Employment expenses: Details of any qualifying work-related expenses you paid personally and haven’t been reimbursed for.
• Other employment income: Details of bonuses, share schemes or other taxable payments not already reflected in the information provided.

If you’ve had more than one employer during the year, make sure you have the relevant information for each employment.

Your accountant may also ask for details of any tax refunds or underpayments relating to previous years that have been collected through your PAYE tax code.

2. Self-employment income and expenses

If you’re a sole trader, you’ll need sufficient records to calculate your business profit or loss.

Depending on how you maintain your accounts, this might include:

• Sales invoices: Details of income earned through your business.
• Business expenses: Receipts and invoices for purchases and other business costs.
• Bank statements: Particularly where these are needed to reconcile business transactions.
• Mileage records: If you’re claiming business mileage.
• Equipment purchases: Details of computers, tools, machinery or other business assets.
• Other business records: Including stock, amounts owed and outstanding bills, where relevant to your accounting method.
• CIS deductions: If you work as a subcontractor under the Construction Industry Scheme, provide your monthly payment and deduction statements showing the tax deducted by contractors.

If you use bookkeeping software, much of this information may already be available in your accounting records.

It’s important to remember that not every business expense is automatically tax deductible. The rules depend on the type of expenditure and how it’s used.

For further guidance, read our article on what business expenses you can claim as a sole trader.

3. State Pension and private pensions

Pension income is another area where information can sometimes be overlooked.

State Pension

If you receive the State Pension, you’ll need the amount you’re entitled to for the relevant tax year.

The State Pension is generally taxable, but tax isn’t deducted from it before you receive it.

The amount required for your tax return may differ from the total payments received into your bank account, particularly where payment dates fall across tax years.

You can usually obtain this information from your State Pension records or by contacting the Pension Service.

If you’ve appointed an accountant as your authorised tax agent, they may also be able to obtain your State Pension figures directly from HMRC, meaning you won’t necessarily need to provide this information yourself. This depends on the information and access available to the authorised agent.

Private and workplace pensions

For private or occupational pensions, gather:

• P60s: Showing pension income and tax deducted.
• Pension statements: Where a P60 isn’t available.
• Lump-sum payment details: If you’ve withdrawn money from a pension during the year.
• Other pension income: Including relevant overseas pensions.

If you receive income from several pension providers, you’ll need the information for each one.

4. Bank and building society interest

Interest earned on savings can be taxable, even if your bank hasn’t deducted any tax.

You’ll need details of interest received during the tax year from accounts such as:

• Current accounts: Where interest is paid.
• Savings accounts: Including easy-access and fixed-rate accounts.
• Building society accounts: Including accounts held with different providers.
• Joint accounts: Your share of the interest received.
• Overseas savings accounts: Where applicable.

Many banks and building societies provide an annual interest certificate or tax summary.

You should include all relevant accounts, even if you believe the interest falls within your Personal Savings Allowance.

Remember: Interest earned within an ISA is generally tax-free and does not normally need to be included on your Self Assessment tax return.

5. Dividend income

If you own shares or receive dividends from a limited company, you’ll need details of the dividends received during the tax year.

This could include dividends from:

• Your own limited company: Supported by dividend vouchers or company records.
• UK-listed companies: Such as shares held through an investment platform.
• Investment funds: Where distributions are taxable.
• Overseas companies: Including details of any foreign withholding tax.

Investment platforms often provide a consolidated tax certificate or annual tax statement, which can make gathering the information easier.

If you own shares in several companies or use multiple investment platforms, remember to check them all. Give your accountant the figures even if you think they fall within the Dividend Allowance.

Dividends held within an ISA are generally exempt from UK tax and do not normally need to be declared.

6. Rental property income and expenses

If you receive rental income, you’ll need details of the income and expenditure relating to each property.

This typically includes:

• Rental income: Rent received during the relevant period.
• Letting agent statements: Showing rent collected and charges deducted.
• Repairs and maintenance: Invoices for qualifying work carried out.
• Insurance: Landlord and property insurance costs.
• Service charges and ground rent: Where applicable.
• Mortgage interest: Annual mortgage statements or interest certificates.
• Other property costs: Such as relevant professional fees and replacement domestic items.

Not all property expenditure receives the same tax treatment.

For individual landlords, finance costs for residential rental properties are generally dealt with through a basic-rate tax reduction, subject to limits, rather than deducted as ordinary expenses. Capital repayments on a mortgage are not deductible. Improvements to a property may also be treated differently from repairs.

For more information, see our guide to allowable expenses for landlords.

If a property is jointly owned, your accountant may also need details of the ownership arrangements and any relevant declarations of beneficial interests.

7. Capital gains from selling assets

If you’ve sold or otherwise disposed of certain assets during the tax year, you may need to report the transaction for Capital Gains Tax purposes.

Common examples include:

• Shares: Sold outside an ISA or other tax-exempt arrangement.
• Property: Such as a second home or rental property.
• Cryptocurrency: Where disposals result in reportable gains or losses.
• Other assets: Where Capital Gains Tax rules apply.

For each disposal, gather:

• Purchase details: The original acquisition date and cost.
• Sale details: The disposal date and proceeds.
• Associated costs: Such as qualifying legal fees, broker fees and certain improvement costs.
• Previous losses: Details of capital losses brought forward, where relevant.
• Supporting documents: Contracts, completion statements and investment transaction reports.

Some disposals may need to be reported even where no Capital Gains Tax is ultimately payable.

If you’ve sold UK residential property and have Capital Gains Tax to pay, you usually need to report and pay it within 60 days of completion. Different reporting rules can apply to non-residents. Provide details of any property disposal return and tax already paid, as you may also need to include the disposal in Self Assessment.

8. Foreign income

If you’ve received income from overseas, your accountant may need additional information.

Examples include:

• Foreign employment income: Earnings from overseas work.
• Overseas pensions: Pension payments received from another country.
• Foreign dividends: Dividends paid by overseas companies.
• Foreign bank interest: Interest received from accounts outside the UK.
• Overseas rental income: Income from property situated abroad.

Where foreign tax has been deducted, provide details of the amount paid.

Foreign income can involve additional tax rules, including double taxation relief and the treatment of overseas income in sterling. Tell your accountant about your tax residence and any move to or from the UK. The foreign income and gains rules changed from 6 April 2025, so do not assume that treatment from earlier years still applies.

9. Pension contributions and Gift Aid donations

Certain payments made during the year can affect your tax calculation, even though they aren’t income.

Personal pension contributions

If you’ve made personal contributions to a pension, your accountant may need to know how much you’ve contributed and how tax relief was given.

This is particularly relevant where contributions were made under a relief-at-source arrangement and you’re entitled to claim additional tax relief.

Contributions deducted directly from salary are not necessarily treated in the same way, so it’s important to identify the type of pension arrangement:

• Relief at source: Your provider adds basic-rate tax relief to your contribution. Supply statements showing what you paid and the relief added, including any workplace contributions under this method, so your accountant can establish the gross amount and any additional relief due.
• Net pay arrangements: Contributions are taken from pay before Income Tax is calculated. Relief is normally already given through payroll, so these contributions should not also be claimed as relief-at-source payments on the return.
• Salary sacrifice: You give up salary in exchange for an employer pension contribution. This is not a personal contribution to claim again on your tax return.

If you’ve received a pension savings statement or may have exceeded a pension allowance, provide that information too.

Gift Aid donations

If you’ve made charitable donations under Gift Aid, keep a record of the amounts donated.

These donations can affect the calculation of tax for some taxpayers, particularly higher-rate and additional-rate taxpayers.

Your accountant may also need to check that you’ve paid sufficient UK Income Tax or Capital Gains Tax to cover the Gift Aid claimed by charities.

10. Other information your accountant may need

Depending on your circumstances, you may also need to provide:

• Student loans: Details of Student Loan or Postgraduate Loan repayments and the applicable loan plan.
• Child Benefit: Details of Child Benefit received by you or your partner, where relevant to the High Income Child Benefit Charge.
• Marriage Allowance: Information about any claim or transfer of allowance.
• Tax refunds: Details of refunds already received from HMRC.
• Other taxable income: Including relevant trust income, chargeable event gains or other income not covered above.
• Previous tax payments: Details of payments on account or other payments made towards your Self Assessment liability, if your accountant cannot already access them.

It’s also worth letting your accountant know about any significant changes during the year, such as starting or leaving employment, selling a property, retiring or receiving a substantial one-off payment.

What if I don’t have all my documents?

Don’t panic if you’re missing a P60, interest certificate or other document.

In many cases, you can obtain a replacement directly from the organisation concerned.

For example:

• Missing P60: Contact your employer or pension provider.
• Missing bank interest information: Request an annual interest summary from your bank or building society.
• Missing dividend information: Check your investment platform or contact the company concerned.
• Missing rental statements: Contact your letting agent or review your rental records.
• Missing invoices or receipts: Request duplicates from the supplier where possible.

If you genuinely cannot obtain the information, speak to your accountant before submitting your return.

HMRC allows reasonable provisional figures where final figures are not yet available, rather than delaying the return. These must be identified and replaced with the actual figures when available. If records cannot be recovered and an estimated figure is intended to be final, explain in the return why an estimate was necessary. The correct treatment depends on the circumstances.

Does HMRC already know how much I’ve earned?

HMRC receives information from various sources, including employers, pension providers and financial institutions.

However, you shouldn’t assume that HMRC already has everything needed to complete an accurate tax return.

Information may be incomplete, delayed or missing altogether.

Even where figures are available through your Personal Tax Account, it’s sensible to check them against your own records.

Ultimately, you’re responsible for ensuring your tax return is accurate and complete, even when an accountant prepares it on your behalf.

Do I need to send every receipt and bank statement to my accountant?

Not necessarily.

If your business records are well maintained, your accountant may be able to prepare your tax return using bookkeeping reports, accounts and supporting summaries.

However, they may request additional documents to check particular transactions or confirm the figures.

For personal income, an annual tax certificate or statement is often more useful than providing twelve months of bank statements.

The key is to provide complete, accurate information for every relevant income source, rather than simply sending large quantities of paperwork.

How long should I keep my Self Assessment records?

You must retain sufficient records to support the information included in your tax return.

The retention period depends on your circumstances.

For a 2025/26 tax return submitted on time, this would generally mean keeping records until at least 31 January 2032 if you’re self-employed or have rental income, or 31 January 2028 for other taxpayers without business or rental income.

Records may need to be kept for longer if a return is submitted late, HMRC opens an enquiry or other circumstances apply. Keep purchase and improvement records for assets you still own, as you may need them to work out a capital gain when you dispose of the asset later.

You can generally retain records electronically, provided they remain accurate, complete and accessible.

When is the deadline for the 2025/26 Self Assessment tax return?

The main deadlines are:

PAYE coding is not available to everyone. You must already pay tax through PAYE, for example through employment or a company pension. HMRC also applies limits to the amount it can collect, and you cannot qualify by making a part payment to reduce a bill of £3,000 or more below the threshold.

Payments on account are advance payments towards the following year’s Income Tax and, where relevant, Class 4 National Insurance. They are normally based on half the relevant previous year’s liability for each instalment. They are generally not required if the relevant amount is less than £1,000 or more than 80% of the tax was collected outside Self Assessment.

If you have missed the 5 October notification deadline, contact HMRC promptly. HMRC may give you a different filing deadline when you register late, but this does not automatically move the normal 31 January 2027 payment deadline.

Although the online deadline is 31 January 2027, there’s no requirement to wait until January to submit your return.

Preparing it earlier gives you more time to identify missing information, understand your tax liability and plan for any payment due.

Need help with your Self Assessment tax return?

Preparing a Self Assessment tax return can be straightforward when you have all the information to hand. However, where you have several sources of income, rental properties, investments or more complicated circumstances, it can be easy to overlook something.

At Baldwin’s Accountancy Services, we help individuals, sole traders, company directors and landlords across Lancaster, Morecambe, Carnforth and the surrounding areas with their personal tax affairs.

We can help you identify what information is required, prepare your tax return and ensure relevant income and tax reliefs are considered.

If you’d like assistance with your 2025/26 return, visit our Self Assessment service page or get in touch to discuss your circumstances.