How Far Back Can You Claim a Tax Refund?

Can You Claim Tax Back for Previous Years?

Yes. HMRC permits many types of tax refund and tax-relief claims to be made for previous tax years, provided the relevant claim is submitted within the applicable deadline.

This means that you may still be able to reclaim overpaid tax even if you have only recently discovered the problem.

Previous-year claims can potentially relate to:

• PAYE tax overpayments
• Incorrect tax codes
• Qualifying employment expenses
• Mileage Allowance Relief
• Uniform and specialist clothing expenses
• Professional fees and subscriptions
• CIS deductions
• Errors in a Self Assessment tax return

How Far Back Can You Normally Claim?

For many employment expense and overpaid Income Tax claims, the normal time limit is four years after the end of the relevant tax year.

A UK tax year runs from 6 April until 5 April of the following calendar year.

As of the 2026/27 tax year, the following years will generally still be within the four-year claim window:

• 2026/27: Current tax year
• 2025/26: Normally still claimable
• 2024/25: Normally still claimable
• 2023/24: Normally still claimable
• 2022/23: Normally claimable until 5 April 2027
• 2021/22 and earlier: The normal four-year deadline has generally passed

Claims should not be left until the final day. HMRC must receive a valid claim within the relevant deadline, and incomplete or incorrectly submitted information can create difficulties.

Older years may require individual review where another statutory provision, consequential claim or exceptional HMRC discretion could apply. Acceptance of a late claim should never be assumed.

Why Does the Exact Deadline Matter?

The four-year window moves forward as each tax year ends.

This means that when a new tax year begins, the oldest open year may be approaching its final claim deadline.

For example, a person with an eligible employment expense claim for 2022/23 would normally need to ensure that HMRC receives the claim by 5 April 2027.

After the applicable deadline has passed, HMRC may refuse the claim even where the taxpayer genuinely overpaid.

Common Reasons People Claim Tax Refunds

Many people assume that HMRC will automatically identify and repay every tax overpayment. Although HMRC sometimes issues automatic tax calculations, this does not happen in every situation.

Common reasons for making a tax refund claim include:

• Being placed on an incorrect tax code
• Paying emergency tax after changing jobs
• Having more than one employer
• Leaving a job during the tax year
• Using a personal vehicle for qualifying business journeys
• Paying unreimbursed work-related travel costs
• Cleaning, repairing or replacing qualifying work clothing
• Paying eligible professional subscriptions
• Buying tools or equipment required for employment
• Having tax deducted under the Construction Industry Scheme
• Overpaying through PAYE
• Making an error in a Self Assessment return

More information about eligible costs is available in our guide: What Expenses Can I Claim on My Tax Return?

Can You Claim for More Than One Tax Year?

Yes. If you meet the conditions and remain within the relevant time limits, you may be able to claim for several open tax years.

This can make the total potential refund larger than someone initially expects.

Care worker example

A domiciliary care worker may have used their own vehicle to travel between service users for several years without receiving the full approved mileage amount from their employer.

If the journeys qualify and the relevant years are still open, the worker may be able to claim Mileage Allowance Relief for more than one tax year.

Construction worker example

A PAYE construction employee may have travelled to qualifying temporary workplaces using their own vehicle.

Where the sites and journeys satisfy HMRC's employment travel rules, the worker may be able to claim relief for qualifying mileage across several open years.

Incorrect tax code example

An employee may discover that an incorrect tax code was applied over more than one tax year.

The employee's records can be reviewed to establish whether too much tax was deducted and which years remain open for repayment.

CIS subcontractor example

A CIS subcontractor may have had deductions taken from payments by several contractors.

The deductions must be reported together with income and allowable business expenses through the appropriate Self Assessment process. Depending on the calculation, this may result in a repayment.

What Happens If You Leave It Too Long?

HMRC imposes statutory deadlines on tax refund and tax-relief claims.

If the deadline expires, you may lose the legal entitlement to have the claim considered under the normal rules.

People commonly miss out because they:

• Assume HMRC will contact them automatically
• Believe the refund will not be worth claiming
• Do not realise that previous years can be included
• Wait until they have every document before seeking advice
• Put off checking an incorrect tax code
• Do not understand which claim route applies
• Assume that being employed means their tax must be correct

It is generally better to check your position as soon as you become aware that tax may have been overpaid.

Can You Claim Mileage for Previous Years?

You may be able to claim Mileage Allowance Relief for earlier tax years if you used your own vehicle for qualifying business journeys, paid the costs yourself and were not reimbursed in full at HMRC's approved amount.

The four-year time limit commonly applies to employee mileage claims.

Workers who may have qualifying mileage include:

• Domiciliary care workers
• Community nurses and healthcare workers
• Sales representatives
• Engineers and technicians
• PAYE construction workers
• Utility workers
• Surveyors
• Field-service technicians
• Employees attending temporary workplaces

The journey must qualify as business travel. Ordinary commuting from home to a permanent workplace does not normally qualify.

You should also deduct any mileage amount already paid by your employer when calculating a potential mileage shortfall.

Read our Mileage Tax Relief Explained guide or use our free mileage calculator to estimate a potential claim.

How Much Mileage Tax Relief Could You Receive?

Mileage tax relief is not normally a refund of the full mileage value.

It is generally tax relief on the difference between HMRC's approved mileage amount and what your employer reimbursed.

Tax relief is then calculated using the rate of Income Tax you paid in the relevant year.

For example, if the qualifying mileage shortfall was £1,000 and you paid Income Tax at 20%, the potential tax relief would ordinarily be £200, subject to your individual tax position.

You must also have paid sufficient Income Tax in the year concerned. Tax relief cannot normally exceed the amount of tax you paid for that year.

Can CIS Subcontractors Claim for Previous Years?

CIS subcontractors commonly have tax deducted from their payments before receiving the balance.

These deductions are not necessarily the subcontractor's final tax bill. Income, CIS deductions and allowable business expenses must be reported through Self Assessment to calculate the final position.

A repayment may arise where the CIS deductions exceed the final tax and National Insurance liability.

However, CIS claims are closely linked to annual Self Assessment returns and their filing and amendment rules.

Delays or complications can arise where:

• A tax return was not filed for the relevant year
• CIS deduction statements are missing
• Contractor figures do not match HMRC's records
• Income was omitted from an earlier return
• Business expenses were not recorded correctly
• The normal amendment deadline has passed

Visit our CIS Tax Refund service page for more information about how CIS repayments are calculated.

Can You Correct an Older Self Assessment Return?

Self Assessment returns have separate amendment rules.

A return can normally be amended within 12 months after the statutory filing deadline for that return.

For example, an online return for 2024/25 would normally have a filing deadline of 31 January 2026 and an amendment deadline of 31 January 2027.

Once the normal amendment window has closed, it may be necessary to consider an overpayment-relief claim instead.

An overpayment-relief claim has specific requirements. It generally needs to:

• Be made within four years after the end of the relevant tax year
• Identify the tax year concerned
• Explain why tax was overpaid
• State the amount believed to have been overpaid
• Include the required declaration
• Be submitted in the correct form

Our Self Assessment Tax Return service explains how we support individuals who need to file or correct their tax position.

What If You Were on the Wrong Tax Code?

An incorrect tax code is a common reason for PAYE employees to overpay Income Tax.

A tax code may be wrong because:

• HMRC has outdated employment information
• A previous employment remains open on HMRC's records
• Benefits or expenses have been included incorrectly
• An emergency tax code was applied
• Your Personal Allowance was allocated incorrectly
• You had more than one job or pension
• An old adjustment remained in your code

HMRC may reconcile some PAYE overpayments automatically, but you should not assume that every error will be corrected without action.

If the incorrect code affected earlier open years, those years may also need to be reviewed.

Learn more on our PAYE Tax Refund service page .

What If You Have Changed Jobs?

Changing jobs is another common reason for overpaying tax through PAYE.

This can occur where:

• You move directly from one employer to another
• Your new employer does not receive your P45 promptly
• You are placed on an emergency tax code
• Your old and new employments overlap on HMRC's records
• You have multiple employers during the same tax year
• You stop working before the end of the tax year
• Your Personal Allowance is divided incorrectly

If you have changed jobs during any of the open tax years, it may be worth checking your P45s, P60s, payslips and HMRC employment record.

Can You Claim Work Expenses for Previous Years?

Employees may be able to claim tax relief on eligible expenses paid personally and not fully reimbursed by their employer.

Depending on the employment, qualifying expenses may include:

• Business mileage
• Travel to temporary workplaces
• Professional fees and approved subscriptions
• Uniform cleaning and maintenance
• Tools required for the job
• Specialist work clothing
• Qualifying accommodation and subsistence
• Other necessary employment expenses

You must normally have paid the cost yourself, used it for your work and paid Income Tax in the year being claimed.

If your employer reimbursed only part of an eligible expense, you may be able to claim relief on the unreimbursed portion.

How Do You Make a Previous-Year Claim?

The appropriate claim route depends on the type and value of the claim and whether you already complete Self Assessment.

A claim could potentially be made through:

• HMRC's online employment expense service
• A P87 employment expense form
• A Self Assessment tax return
• An amendment to an existing tax return
• A formal overpayment-relief claim
• Another relevant HMRC repayment process

If you already complete Self Assessment, eligible employment expenses will normally need to be claimed through your tax return rather than a separate P87 claim.

Employment expense claims of more than the applicable P87 limit may also need to be made through Self Assessment.

Selecting the wrong route can lead to rejection or delay, particularly where a claim relates to an older tax year.

What Information Will You Need?

The documents required will depend on the type of overpayment or expense involved.

Useful information can include:

• Your National Insurance number
• Your Unique Taxpayer Reference where applicable
• Employer names and PAYE reference numbers
• Employment start and end dates
• P60s
• P45s
• Payslips
• Tax-code notices
• Mileage logs
• Work-location and journey details
• Employer mileage statements
• Receipts and invoices for work expenses
• CIS payment and deduction statements
• Previous Self Assessment returns
• Relevant HMRC letters

Do not automatically assume that you cannot claim because one document is missing.

Other records may be available from employers, contractors, bank statements, online HMRC accounts or previous advisers.

However, a claim must still be based on accurate, reasonable and supportable information.

How Much Could You Reclaim?

The amount depends on why tax was overpaid and how many eligible years remain open.

Relevant factors include:

• The amount of Income Tax paid
• Your tax rate in each year
• The value of qualifying expenses
• Employer reimbursements
• The mileage completed
• CIS deductions suffered
• Your total taxable income
• Other liabilities owed to HMRC
• The number of open tax years

Tax relief on an expense is not normally equal to the full cost of the expense.

For example, £500 of qualifying expenses would ordinarily produce £100 of tax relief for someone who paid tax at 20%, subject to their wider tax position.

A CIS repayment is calculated differently because CIS deductions are set against the subcontractor's final Self Assessment liability.

How Long Does a Previous-Year Tax Refund Take?

There is no single HMRC processing time covering every previous-year refund.

Processing time can depend on:

• The type of claim submitted
• The number of tax years included
• Whether HMRC requires supporting evidence
• Whether employer or contractor records match
• The complexity and value of the claim
• Whether the claim is selected for additional checks
• Whether outstanding returns or tax liabilities exist
• HMRC's workload

Older claims may require HMRC to review archived employment, deduction or tax-return information, which can add to the processing time.

Read our guide: Why Is My Tax Refund Taking So Long?

Common Mistakes That Can Prevent a Refund

People often miss valid claims or experience delays because they make avoidable assumptions.

Common mistakes include:

• Assuming HMRC will identify every overpayment automatically
• Thinking that all previous tax years are permanently open
• Waiting until the final claim deadline
• Claiming ordinary commuting as business mileage
• Ignoring mileage already paid by an employer
• Claiming expenses without evidence or a valid basis
• Failing to include previous employments
• Never checking tax codes
• Forgetting CIS deductions from one or more contractors
• Using the wrong HMRC claim route
• Submitting duplicate claims
• Failing to respond to HMRC requests

Another mistake is assuming that a small annual entitlement is not worth checking. A relatively modest claim across four open tax years can become a more meaningful total.

Frequently Asked Questions

Can I claim tax back for the last four years?

Many employment expense and overpayment-relief claims can be made within four years after the end of the relevant tax year.

The exact years available change as time passes, so the deadline for each tax year should be checked.

Which is the oldest tax year I can currently claim?

During the 2026/27 tax year, 2022/23 will generally be the oldest year still open under the normal four-year rule. The usual deadline for that year is 5 April 2027.

Can I claim even if I changed jobs several times?

Yes. Changing jobs can cause PAYE overpayments, particularly where P45 information, tax codes or overlapping employment records were not handled correctly.

Can I claim without all my P60s or payslips?

A missing document does not automatically prevent a claim. Relevant information may be available through HMRC, former employers, bank records or other supporting evidence.

The claim must still use accurate and supportable figures.

Does HMRC automatically refund overpaid tax?

HMRC automatically reconciles and refunds some PAYE overpayments, but not every entitlement is identified or paid without a claim.

Can I claim mileage for four previous years?

Potentially, yes, where the journeys qualify, you paid the costs, your employer did not reimburse the full approved amount and each year remains within the claim deadline.

Can I amend an old Self Assessment return?

A return can normally be amended within 12 months after its statutory filing deadline.

Once that window has closed, a properly prepared overpayment-relief claim may need to be considered, subject to its own conditions and four-year time limit.

Can HMRC accept a late claim?

HMRC has limited discretion in certain exceptional circumstances, but acceptance of a late claim is not guaranteed and should not be relied upon.

Is it worth checking whether I am due a refund?

Yes. A review can identify whether tax was overpaid, which tax years remain open and whether the potential amount justifies making a claim.