NIM37001 | Refunds: Class 1: General
From HM Revenue & Customs · National Insurance Manual
Regulations 51-54, 57 and 59 of the Social Security (Contributions) Regulations 2001 (SSCR 2001) (SI 2001 No 1004)
A refund of Class 1 NICs is available if a contributor pays above the annual maximum or wrongly pays Class 1 NICs due to an error which occurred at the time of payment.
Guidance on the annual maximum can be found at NIM37010.