It is common for employers to offer car allowances to employees who use their own cars for business travel. Often, employers have a policy to reimburse mileage at the company car fuel advisory rates or some other amount less than the AMAP rates for these employees. The AMAP rates are £0.45 for the first 10,000 miles and £0.25 thereafter.
Where reimbursement has been made at less than the AMAP rates, employees are entitled to claim tax relief on the difference between amount received and the AMAP rate. For example, if an employee is reimbursed at an average rate of 10p per mile and travels 10,000 business miles in a tax year, they are entitled to claim a tax deduction of (£0.45 - £0.10) x 10,000 miles = £3,500.
Up until now, there has been no clear precedent around claiming any relief for NICs, amounting to a mismatch between the tax and NIC treatment.