PAYE61025 | Employment maintenance: create employment: Employer responsibilities
From HM Revenue & Customs · PAYE Manual
When an employee starts in employment the employer must ask the employee for Parts 2 and 3 of form P45 given to them by any previous employer (or by the Department for Work and Pensions Office if the employee was previously unemployed and claiming Jobseeker’s Allowance).
An employee may not give a form P45 to a new employer because
The last employer failed to give them the form
It has been lost
The employee was previously self-employed or at school or college
The employee does not want the new employer to know what the previous employer paid or the code operated
Or
For some other reason
If the employee fails to provide the P45, the employer is required to
Submit starter information on their Full Payment Submission (FPS)
Unless
The employee earns below the taxable limit and states that this is their only or main employment
In these circumstances the employer must complete a starter checklist or equivalent record of an employee’s starter declaration for three tax years for audit purposes.