PAYE72015 - PAYE operation: payments for PAYE purposes: conditional payments
If an employee's entitlement to a payment depends on a future condition being met, taxshould not be deducted until that condition is met.
For example, if a contract says a bonus will be paid for the year ending 31 December oncondition that the employee still works for the company on the following 1 June, PAYEshould be operated on 1 June.