How to pay for missing National Insurance Years

Hello, Please can you tell me if it is still possible to pay for gaps in my National Insurance by cheque ? I am not yet of pensionable age and the pension website shows the increase that I will get in my state pension if I pay for my missing years of National Insurance. I can see quite clearly on the pension website which years I need to pay for and how much this will cost so can see no reason to contact the Future Pension Centre. Many thanks Sarah

Hi,
Please refer to guidance at:
Voluntary National Insurance: How and when to pay
Thank you

Hello, Thank you for your reply to my enquiry, I have clicked on the link and the information there is helpful up to a point but states that I need to include an 18 digit reference number which I do not have as I have not got an HMRC payment request. My apologies if I am missing something, I have seen another reply to this question that made no mention of needing the 18 digit reference number but it was from some time ago so I thought I would enquire rather than follow that advice and not do things correctly.

Hi,
If you have already confirmed with the Future Pension Centre that the years you are paying for will boost your pension entitlement, you can contact National Insurance on 0300 200 3500 or contact us using our webchat service on the GOV.UK website.  Contact HMRC
In turn, we can provide your 18 digit reference number over the phone or the chat service.
Thank you.