I joined current employer on 20th March 2023 and was supposed to be paid me sign-on bonus with my first payroll (that was at the end of March 2023) as written in my contract. However, HR made an error and did not pay my sign on bonus in March. Upon enquiry they paid it in April despite my request to sort the issue and pay this in previous year's arrears. However, HR became unresponsive and went ahead paying as part of this year's payment. This means my annual limit is pushed into > £100,000 bracket. This has tax and child care benefits implications on me and causing great concern as I am effectively financially worse with the bonus than if there was no bonus payment at all. Is there a way to get this payment classified as such that it is treated as previous year's arrears (as I was contractually bound to be paid this in my first payroll that was paid in March) by contacting HMRC?