Improvement: Payroll Additional NI category support

Hi all!

We are very pleased to announce that due to popular demand, our developers have now added support for a new NI category letter X. This would be suitable for employees who do not have to pay National Insurance, for example, because they’re under 16.

For further details please see this HMRC documentation:

https://www.gov.uk/national-insurance-rates-letters/category-letters

Thanks!

Tommy