I have a client who wants to run their Year End Payroll. They have asked if they can change all their employees on 647L to to 747L for the new tax year, without having received their tax notices? Also can she change all tax month 1 notices?
To re-iterate what Nick and Peasie have said, all employees with a tax code ending in L should have 100 added to their tax code (i.e. 647L becomes 747L, 553L becomes 653L etc). You do not carry forward W1 M1 on any codes.