From October 2020 HMRC has changed its systems so that you only need to claim the Working at Home allowance once. You will automatically get the allowance for the whole of this tax year. You do not need to be just working at home full time.
The allowance can been claimed if you only work part time from home or you only work one day a week at home.
HMRC says: “We recognise that the working from home situation is very fluid this year, so we’re accepting claims for the full year’s expenses. That includes even if people have only worked from home for some of the year, to avoid needing to contact us if you have to work from home again.”
New claims should be made via www.gov.uk/tax-relief-for-employees/working-at-home You will need your government gateway ID to claim. If you do not have one then this can be created when making the claim.
If you have already put a claim in for this tax year? you will not miss out, You will need to make another claim on form P87 and claim the full amount of £312.