You can also use the online form service if you don’t qualify for a current HMRC campaign, but haven’t declared the right amount of income or tax for one or more of the following:
Capital Gains Tax
National Insurance contributions
You’ll need to sign in to, or set up a Government Gateway account to use the service.
Tax, interest and penalty calculators
You can use one of the following calculators to help you work out the tax, interest and penalties you owe if your tax affairs are straightforward, and you’re only entitled to basic personal allowances: