Is it worth buying additional NI years as a high rate tax payer?


I worked as a nurse on the NHS from leaving school to retirement at age 60 without any break in service. I have a full NI record from 1978 to 2019/20 (44 years) when I retired.
State pension forecast:
Estimate based on NI contributions up to April 2022 is £164.87 per week
Estimate based on NI contributions up to April 2025 is £180.74 per week
The most I can increase my forecast to is £185.15
I currently have no contributions from 2020/21 so I will be short 5 years to get the £180.74. The 2 years I am currently short will cost approximately £800 each, so assuming they all cost about that (not convinced they will) that is a £4k investment for a return of £15.87 per week before tax and £9.52 after tax as my state pension pushes me into the 40% tax bracket. So, I’m going to have to draw my pension for at least 8 years for it to start making it worth the investment though I appreciate that it will be inflated over that time so could be less though I also foresee the cost of buying those years going up to so will probably cancel each other out.
I’m on the fence as to whether it’s worth that investment – what do you think?
There is also the added pressure where it states that if I don’t buy the 2020/21 year buy April 2023 the price may go up but don't know how real that is.
Replies
Estimate based on NI contributions up to April 2022 is £164.87 per week
Estimate based on NI contributions up to April 2025 is £180.74 per week
The most I can increase my forecast to is £185.15
I currently have no contributions from 2020/21 so I will be short 5 years to get the £180.74
You only need 4 years to reach the full £185.15.
The first 3 will add £5.29 each and the fourth adds the final £4.41.
If you can get 4 years for ~£3,300 that's adding £22.32/week to your pension (2023:24 value). £1,160/year.
Even after 40% tax that's still £696/year so your initial outlay will be recouped fairly quickly. And that £696/year is only ever going to increase and could be paid for 30+ years.
Everyone else reaching State Pension age after 5 April 2016 is under transitional rules.
Details here,
https://www.gov.uk/new-state-pension/how-its-calculated