NOTE:
Category X reference on an employees P11 is because their total NI contributions for the pay run are zero. Their earnings in the pay run are below the LEL threshold, or if the only payment made is a pension payment. Also, a category X reference on an employees P60 means total NI contributions for the tax year are zero. Their earnings in the pay run are below the LEL threshold, or the only payment made was a pension payment. For more information, read the HMRC article: Guide to PAYE and National Insurance Contributions atgov.uk.