Hi wyllis Cheung
Please check the year that the new code number relates to.
If for 2024/2025 and you have not operated this then submit the Final Payment Summary using the old code number.
There will be no need to issue any revised P60.
HMRC will then review the return made by you and take any action necessary.
Please see guidance at:
Running payroll: Overview
If the code number is for 2025/2026 then amend the customers code number against their April salary and submit your monthly/weekly payroll as normal.
If you have any issues then please call:
Employers: general enquiries
Thank you.