All new employees should complete the HMRC approved starter checklist even if they present you with a completed P45.
HMRC are actively checking up on employers who are not using correct PAYE codes.
Page 1 of the starter checklist asks the individual to tick box A, B or C next to statements: this is my first job since claiming state benefits; only job; or second concurrent job or pension.
If all choices are left blank, the employer should choose option C and the employer is given a PAYE code of 0T/1. That PAYE code means the employee is not given a personal allowance and may be over-taxed. HMRC may take some months to correct the PAYE code, during which the employee will be short of cash and thus unhappy! This does not help you retain staff. Please help your new employees to complete the starter checklist correctly as some people may not understand the language used.
Do you download any new PAYE codes from HMRC before each payroll run? Most PAYE codes are delivered electronically and you need to check using your payroll software whether new codes have been issued to your employees. Report to HMRC any oddities with PAYE codes, such as an incorrect name or NI number for an employee.