Backdating your claim is allowed
HMRC lets you backdate mileage tax relief claims for up to four tax years. If you have never claimed before, you may be owed a significant refund covering several years of work travel.
Why backdating matters
Many employees discover mileage relief late. They may have been underpaid for years but never knew they could claim. Backdating ensures you recover everything you are entitled to, not just this year’s shortfall.
How much could you get back
Take an example of a community nurse who drives 5,000 miles per year and is paid 25p per mile. The HMRC rate for the first 10,000 miles is 45p. That is a 20p gap for every mile. Over a year the shortfall is £1,000. At 20 percent tax relief that means £200 refunded per year.
Backdating four years means a refund of £800. For workers with higher mileage, the totals can be much larger.
What records you need
To claim backdated relief you need mileage logs or records of your business travel. These can be diaries, spreadsheets, or mileage tracking apps. You do not need fuel receipts because claims are based on miles driven, not petrol spend.
How to backdate your claim
Gather your mileage records for up to four past tax years.
Work out your total mileage and compare with what your employer paid.
Complete form P87 for each tax year or include it in your Self Assessment.
Submit the claim to HMRC or let TaxBax manage the whole process.
Why choose TaxBax
Backdating involves multiple forms and can feel overwhelming. TaxBax prepares everything, checks your eligibility, and ensures HMRC receives a complete claim.
Check how much you could reclaim from past years with TaxBax and start your backdated mileage claim today.
