Information provided on Form SO41

In Box 4 ("In reply to your S040 of..."), for "period under our legislation", does HMRC answer on the basis of the dates someone was covered by the NHS ie had a valid NHS number or on the basis of the dates for which NICs were paid? Similarly, in Box 5 (" Insurance period"), does HMRC enter the dates someone was covered by the NHS ie had a valid NHS number or the dates for which NICs were paid?

Hi,

The periods shown on a S041 certificate (which is a reply to a S040) relate to periods of Insurance (where NICs have been paid), or periods of residency in the UK, not the periods when someone has had a valid NHS number. However, without sight your personal certificate, we are unable to answer specifics on this forum.
Please contact the National Insurance team and we can check your records, and answer any further queries you may have. 

National Insurance: general enquiries

Thank you.