I have done my online self-assessment for tax year 2020-21. The sum HMRC are asking me to pay on the final screen does not deduct the two Payments on Account sums for 2020-21 I paid in advance, in January and July 2020.
I would have thought that in this day and age HMRC's calculation of the sum due would have deducted Payments on Account amounts paid?
That would be too easy - in some respects factoring in payments on account into the tax computation of the tax for the year could perhaps confuse some more than help - note there are two payments on accounts totals - what you should have paid and what you did pay - so always room for confusion . Simply check the "view acount" section and this will detail the payments on account , once return is processed everything should beupdated so you can check the overall current position. Note those payments on account may change downover when return is submitted if tax due on account is lower than your year tax suggests should be the case.
Therefore, do I need to manually calculate the amount I have to pay HMRC for 2020-21 (and the next Payment on Account) after deducting the 2020-21 Payments on Account amounts already paid?
As above simply view payments made on acount from the viewacount/tax years scren to see whats been paid on account and manually adjust payments if needs be - dont forget to add in any payments on account due 31/1/2022 based on this submission
Things will be much clearer when return processed and all recalculations are done - you may want to take priontouts fo beforer and after though .
Do I need to notify HMRC somehow (how?) or will their calculators automatically calculate the Payments on Account amounts paid? I don't wish to suffer any issues because they think I have underpaid!
Nope its par for the course payments on account dont show up in "tax comp" however they are always there and up to date when you navigate around the liabilities due section - there will be a summary overview once return is processed and that should fully match what you have manually calculated.
No need to notify hmrc - generally the system is robust in getting correct totals and overall summary (certainly with regard to not mising payments on acount) - the tricky bit can be working out where stuff is allocated if numbers are updated and replace differenet previous sums - if you goi back into calcs you should be able to follow it all through in theory. HMRc arent perfect though so if it doesnt make sense when the mop flops alwasy ask questions.