Voluntary NICs-is 2020-21 a 53 week year?

[sloth]

I paid voluntary NICs last tax year by cheque and assumed it was a 52 week year, only to be asked for a further week's contribution.

Anybody know if the current year is 52 or 53 weeks?

I understand it's difficult to get through on the phone at the moment or I'd just call them.

[sloth]

I managed to speak to somebody WFH who was very helpful, and she told me it is definitely a 52-week year, so £158.60 total.