Covid working from home on Self Assessment

NoCluedo

I am still clueless after talking to HMRC about my working from home entitlement.
I am a teacher and higher tax payer. I complete self assessment. I am not able to use the mini site for the covid working from home. I thought I was entitled to £125 but I get to the page about employer expenses and to calculate myself how many weeks I worked from home. Adviser told me that it is a common misconception that people get the full amount of £125 as it is just a % of that. This contradicts everything I have read and heard about, especially on MSE.
Who can guide me exactly where to go and what amount to put in for 2020-2021? Also, the claim for March 2020 when my school first closed. I have been working solid days often straight from 7:30am to 11:59pm with the odd break on the couch - my wife would love me to replace the sagged section of that couch as it wasn't designed as a 'home office' Just a % of £125 won't get that far! :-) 

[Deleted User]

The claim is £6 per week or £312. As a 40% taxpayer your tax would reduce by 40% of that - £124.80. 

In the employment section answer ‘yes’ to the ‘Do you want to claim any expenses against this employment?’ question and put 312 in the ‘Other expenses and Capital Allowances box’.

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

Dazed_and_C0nfused

If you were WFH due to Covid-19 then you can claim expenses of £312 (£6 x 52).  These go on the employment page (make sure you tailor the return correctly).

The tax saving depends on your personal circumstances.  Most likely it will be £124.80.

To check your tax saving you should complete (but don't submit to HMRC) your return without the expenses.  Check the calculation and note the tax owed/overpaid.

Then add the expenses and check the revised calculation and note the difference.  That is the personal tax saving for you.

If you have filed an incorrect return for 2019:20 then you have a few days still to submit an amended return.  The tax saving is likely to be < £5 for that year. 

NoCluedo

I expected HMRC to tell me that but they didn't. You have been very helpful. Thanks.