Called up HMRC this evening. After about 30 minutes on hold I got through to a helpful Geordie who put a note on my file allowing me to pay late for the pre 2019 years despite missing the 31 day deadline in the letter that arrived last week, and also took details of which years I was planning to pay. Sent the payment from my UK account after the call. We’ll see how long it takes for them to be allocated… (she quoted 8 weeks)
Something else that may be of interest to those on here: I was confused why my estimate on the State Pension Forecast checker tells me I need 21 more years on top of the 12 I already have. Clearly that is only 33 years, not 35. In addition my estimate based on making no further contributions is showing £94.17/week, which is *not* 12/35s of the current full £230.25/week.
Some Googling tells me that the requirement for exactly 35 years only applies to those born after 2000, whose entire working lives will therefore be under the new rules that came in in 2016. For everyone born earlier a calculation was done in 2016 based on your contributions to date to determine a starting amount. Each year of post 2016 contributions increases this by 1/35 until you reach the max amount.
The end result of that is that you may need more or less than 35 years. Someone on the MSE forum reports achieving the full pension entitlement with only 26 qualifying years:
State pension forecast and missing years – Should I pay the shortfall?
This thread has more details on the transitional calculations:
State Pension
As I understand it, once you get to the stage where the forecast says:
£230.25 is the most you can get
You cannot improve your forecast any more.
(Or whatever the current max weekly payment is in whatever future tax year you reach this stage) then there is no reason to contribute any further years, even if you don’t have 35 qualifying years of contributions.
I feel like this is not well explained by any of the official guidance, but at least you can use the forecast to see exactly how many years you personally need to get to the maximum.