National Insurance Contributions are due on all benefits and on any reimbursed expenses that have a private use element (i.e. are not for a 100% business use). Broadly speaking, out and out benefits attract Class 1A National Insurance contributions. For convenience these types of benefits are easily identifiable on the P11D form with their cash equivalents having to be entered in brown boxes.
The P11D(b) form is used to sum up every employees benefits (as appearing on the brown boxes of the P11D forms) and then to apply the secondary Employer’s NIC rate in force for any particular year, to calculate the amount of Employer’s Class 1A NIC due.
Any benefits and expenses that do not appear in a brown box on the P11D may still attract National Insurance. The default setting for entries in the blue boxes for the P11D is no Class 1A NIC due but these default settings can be adjusted to make individual benefit types attract Class 1A NIC. These adjustments appear on the reverse of the P11D(b) form.
Class 1A NIC is due to be paid to HMRC Accounts Office by 19th July, two weeks after the P11D submission deadline date of 6th July.
Any private use associated with reimbursed expenses will not attract Class 1A NIC. They will instead attract Class 1 NIC and this should be collected through the payroll at the time the private use occurred.