Class 1 National Insurance (NI) is a type of tax that is levied in the UK on the earnings of employees. Class 1 NI contributions are paid by employees and are used to fund the UK's state benefits and pension system.

Class 1 NI contributions are calculated as a percentage of an employee's earnings and are paid through the payroll system. The rate of Class 1 NI that is paid depends on the employee's earnings and their employment status. Most employees pay Class 1 NI at a rate of 12% on earnings above a certain threshold, known as the lower earnings limit, and a rate of 2% on earnings above a higher threshold, known as the upper earnings limit.

Class 1 NI contributions are an important source of funding for the UK's state benefits and pension system and are an important consideration for both employees and employers. It is important for both parties to understand the Class 1 NI rules and to accurately pay and report contributions.