Two directors were appointed in January 2025 and have been employees since before the start of this tax year. I have tried to find an example computation for Month 12 to check that they have paid the right amount of NI, but can't see one that applies to this specific circumstance. I have used HMRC's "Check your calculations manually" to perform some calculations: For months 1 to 9, my payroll software agrees with HMRC's each month calculations as non-directors. For their directorship period, I have input the appointment date, their M10-M12 earnings and the NI they paid in months M10 and M11 to get a figure for M12. I can then tell my software to overwrite the NI figure it is suggesting. Please could you tell me if this is the right approach, or where I could find a specific example? Thank you.