Thanks for your question - I am Sam and I am one of the Uk tax experts here on Just Answer.
Did your husband pays these voluntarily each year or has recently made a payment to reflect several years? If not where did you believe the credits would come from?
Did he continue to pay Class 2 National Insurance each month or quarter (changed to annually from 2014/2015)
Pleae advsie further
NO I am sorry your information and understanding is wrong - they still have to be paid from the individual as a rule
If an individual is below the National Insurance limit for Class 2 National Insurance, then there is an option to make this payments to the National Insurance office either through the year of year end or HMRC would have applied a small earnings exception certificate and not charged them.(this has now been scrapped and the option to pay them yearly applies to all regardless of their income/turnover for self employment (just those below the limit are still given the option)
Then you have Class 3 contributions these are also voluntary but usually for people either living abroad or those that have not made full contributions over the years and wish to bring their full record up to date.
Your husband would not have been credited with any contributions unless (and these are just the main ones)
1) he was claiming Job seekers allowance or other benefits such as sick pay where a credit is paid
2) Up until 2009 parents who were the named claimant for child benefit also received credits - but his has now been replaced by parents of under 12 where the family as a whole are on low incomes and these still have to be claimed for
3) Tax credits with a disability premium
The only option your husband will have now is to make Class 3 voluntary contributions but I am afraid these will cost £14.10 per week to bring his record up to date (this is 733.20 per missing year and to get a full record towards a state pension its 30 years - but this will provide the FULL state pension whereas self employed Class 2 contributions would only ever have provided a basic state pension (the lower end of entitlement)
Please let me know if I can assist further