Backdating Working From Home allowance

newbie8

Apologies if this has already been mentioned.. 
How do I backdate WFH allowance.. Based at home for the last 15yrs and not claimed before. So looking to backdate the claim to as far as possible but it's asking me about number of rooms, how much utilities are etc. Have I selected the wrong option? 
Is water also included? 
Thanks

Dazed_and_C0nfused

The furthest back you can possibly claim is the 2016:17 tax year.

And any claim for 2016:17 must be made by 5 April 2021.

Do you think you are eligible for tax relief on the standard £4/week or do you wish to claim actual costs?

Are you certain you are eligible to claim?

https://www.gov.uk/tax-relief-for-employees/working-at-home

newbie8

Hi,
Have all the bills etc. which is best .. to claim the £4 tax relief or claim actual costs? 
What's the difference? 
Thanks,

Dazed_and_C0nfused

You cannot claim £4/week tax relief.

It is tax relief on £4/week.  Which is worth 80p for most people.

If you are eligible the £4/week route is easy.  Working out actual costs would be more complicated and much more likely to be questioned by HMRC.

Which is worth more to you would depend on the actual costs involved.