Do I need to pay National Insurance as a sole trader?

As a sole trader you pay Class 4 National Insurance on your profits above a set threshold, collected through Self-Assessment alongside your Income Tax. Class 2 National Insurance, which used to be a flat weekly charge, is no longer compulsory for most self-employed people below the small profits threshold, though you can still choose to pay it voluntarily to protect your State Pension record and entitlement to certain benefits. Rates and thresholds are reviewed most tax years, so it's worth checking the current figures or asking your accountant when working out what you owe.