Anyone who earns income in the UK may need to pay National Insurance (NI) - whether you're employed or self-employed.
The amount you pay will vary depending on your income and employment status.
You can use our calculator below to work out how your NI contributions will be in the current tax year.
Alternatively, to find out how your bill is calculated, see our guide to National Insurance rates.
Do I need to pay National Insurance?
For the 2018/2019 tax year, employees must pay National Insurance if they earn more than £8,424 in the year.
Self-employed workers will pay Class 2 contributions if they earn more than £6,205, in addition to Class 4 if they earn more than £8,242.
Our guide to National Insurance rates sets out the full rates and thresholds.
How do I pay National Insurance?
If you're an employee, National Insurance will be deducted from your salary before you receive it, along with any income tax. You can work out your deductions with our income tax calculator.
If you're self-employed, you'll usually need to pay via your self-assessment tax return.
To get a head-start on your tax return, use the Which? tax calculator to work out your tax bill and submit direct to HMRC.