We are calculating the income tax and NIC due under our PSA. There are quite a few employees that joined midway through the year. When considering what marginal tax rate to apply to these individuals, should we apportion their total annual salary by the no. of days they have been employed by us in the tax year?
E.g. if an employee's annual salary is £60k but they actually only joined in January 2023, should we use a marginal rate of 20% rather than 40% for the 2022-23 tax year?
Similarly, if their apportioned salary is £12,571, should we apply a marginal rate of 0%?