HMRC are sending out tax statements if you have a tax on account payment due on 31 July 2020, the date for payment will show as 31 January 2021 not 31 July 2020, it is correct and there is an explanation from HMRC. If you don’t owe tax on 31 July 2020 then it won’t apply to you
You can still make the payment by 31 July 2020 as normal if you’re able to do so.
The June 2020 Self Assessment statements show 31 January 2021 as the due date for paying the July 2020 Payment on Account. This is because HMRC updated their IT systems to prevent customers incurring late payment interest on any July 2020 Payment on Account paid between 1st August 2020 and 31 January 2021. The deferment has not been applied for all customers by HMRC and it remains optional.
HMRC will not charge interest or penalties on any amount of the deferred payment on account, provided it’s paid on or before 31 January 2021.