• Payable by both the employee (primary Class 1 contributions) and the employer (secondary Class 1 contributions).
• Both primary and secondary Class 1 NICs are collected through your payroll via the PAYE (Pay As You Earn) system.
• Charged as a percentage of employees' earnings over a certain amount.
• Also applies to a small number of employer-provided expenses and benefits (including childcare vouchers over a threshold of £55 per week).
• Applies only to employees who are aged 16 or over. Employee contributions stop at State Pension age, but employer contributions continue for as long as the employee continues to work.
• There are numerous differed Class 1 categories that apply to employees in different circumstances. These are explained in the later section, 'Class 1 NICs: contribution letters at a glance'.

Note that Class 1 NICs for directors are calculated slightly differently from those for other employees. For more information, see our guide on Employee starts or stops a directorship.

Find out more about payroll calculations for tax and NICs in our Monthly/weekly payroll and form filling section.

• Payable by employers and certain third parties on taxable benefits provided to employees.
• Charged as a percentage of the cash equivalent of the benefits.

Find out more about expenses and benefits in our Expenses and benefits for employers section.

• Payable be employers who have agreed a PAYE Settlement Agreement (PSA) with HM Revenue & Customs.
• Charged on the combined value of the items covered by the PSA and the tax payable by the employer under the PSA.

Find out more about PSAs in our guide PAYE settlement agreements.

• Primary Class 1 collected by the employer through PAYE - see previous table.

• Payable by self-employed individuals.
• Applies only to people who are aged 16 or over but remain below the State Pension age.
• Set at a fixed weekly amount, regardless of earnings.

• These are voluntary contributions that individuals can make to protect their entitlement to social security benefits if they haven't paid sufficient earnings-related contributions.

• Payable by self-employed workers as a percentage of their annual taxable profits.
• Applies only to people who are aged 16 or over but remain below the State Pension age.