18 Digit Ref. Number for overseas payers

Hi, I have read on various threads that this number is needed as reference to any overseas payers who wish to pay the shortfall in years of NI contribution and how it is generated : NI number + letters IC + surname and initials. But for me, and maybe some others, I cannot create 18 digits this way as my surname is too short ( 15 digits in total ) and even if I use all the initials of my first and middle names I still only get to 17 digits. Please can you advise on what to do in this instance. Many thanks.

After speaking by telephone to an HMRC admin worker, a few days after posting this, I was advised that the fact I couldn't make the full 18 digits wasn't so important and 15 numbers were even enough, as the NI number at the beginning was the part referenced in enquiries. Please can an admin worker on this forum clarify this for anybody else reading this post with a similar problem. Thanks.

Hi,
We can confirm that as you are paying overseas National Insurance contributions then your ’18 Digit Reference Number’ is:  Your National Insurance Number + IC + Surname + initial.  
If this does not add up to 18 digits then that is fine.
Thank you.

Many thanks for the confirmation.

I have an issue where whn I put my reference number in (my national insurance number plus I plus surname I get a warning saying "the reference you've added doesn't match the supplier" and it seems to want the 20digit code or something different. Can I get some help regarding this? As it won't let me send the money.

I have an 18 digit ref from some years ago, can I still use this or do you need a new one every time you make a payment? I am not paying from overseas.

Hi AndrewJohn14,
As an overseas customer, your 18 digit reference number is made up of your National Insurance Number followed by ‘IC’ then your surname and initial if possible. The link below will confirm your 18 digit number and our bank details:  
Pay voluntary Class 3 National Insurance
If you have any problems with your bank transfer then you may wish to contact your bank for help.
Thank you.

Hi Nicola Levett,
If the amount you are paying is the same amount you previously paid you can use the same 18 digit reference but if the amount is different you will need to contact our National Insurance team to obtain a new reference number.
National Insurance: general enquiries
Thank you.