If he does not have a Form P45 then you will require the following information:-
full name
gender
date of birth
full address (including postcode)
National Insurance number (if the employee knows it)
Then he will need to confirm one of the following:-
A. This is their first job since last 6 April and they have not been receiving taxable Jobseeker's Allowance, Employment and Support Allowance, taxable Incapacity Benefit, state pension or occupational pension.
B. This is their only job, but since last 6 April they have had another job, or have received taxable Jobseeker's Allowance, Employment and Support Allowance or taxable Incapacity Benefit. They do not receive state or occupational pension.
C. They have another job or receive a state or occupational pension.
If A apply a 944L tax code. If B apply a 944L W1/M1 tax code. If C, apply a BR Tax Code.
Then just calculate wages using the PAYE system as normal.
