Yes you can pay shortfall years, the question is if it's worth it. There is a 6 year time limit to pay for them, on that basis the furthest back anyone can go is 2013, earlier years are gone. The exception to this is a small group of women who have had insufficient notice to the changes to their state pension entitlement. These are mainly women who do not have their own NIC but have been dependent on their husbands contribution record. Let's not forget, under the old system, the maximum would be around £125pw, regardless of a 30/40/50 year contribution record. To pay £749 for an additional £4.20pw seems extremely good value to me, it pays for itself in 3 years.