National Insurance Contributions — Employer Monthly Returns
Employers operating the Isle of Man ITIP (Income Tax Instalment Payments) system must submit monthly returns detailing employee earnings, income tax deducted and National Insurance contributions. Payments are due by the 19th of the following month.
Who this applies to
- All Isle of Man employers with employees earning above the National Insurance lower earnings limit (£145 per week / £7,540 per year for 2025/26)
- Directors of Isle of Man companies receiving a salary through ITIP
What to file
Monthly ITIP/NIC return (P11 equivalent) showing each employee's gross pay, tax code, income tax deducted, employee NIC deducted, and employer NIC payable. Annual reconciliation via P35 equivalent at year-end.
How to file
Via the Isle of Man Assessor of Income Tax's employer online services or by approved payroll software submission. Paper returns are accepted but online is preferred.
Payment due
Combined ITIP income tax and National Insurance payment due by the 19th of the month following the payroll date. Payment via bank transfer to the Isle of Man Treasury.
Penalties for missing this deadline
Late payment interest applies from the due date. Persistent late filing may result in formal enquiry by the Assessor. Failure to deduct and remit ITIP correctly makes the employer personally liable for the tax that should have been deducted.
Filing checklist
- Run payroll for the period using ITIP tax codes issued by the Assessor
- Deduct correct employee income tax at the ITIP rate (10%/20% on income above personal allowance equivalent)
- Deduct employee NICs at the correct rate
- Calculate employer NICs (13.6% above the lower earnings limit)
- Submit the monthly return by the 19th
- Pay combined ITIP and NICs by the same deadline
Common mistakes to avoid
- Using UK PAYE tax codes instead of Isle of Man ITIP codes — these are not identical and using wrong codes results in incorrect deductions
- Failing to update ITIP codes when the Assessor issues a new code during the year
- Omitting employer NICs — some employers erroneously only remit the income tax element
- Missing the 19th deadline in months with public holidays that shift banking availability
Never miss a Isle of Man deadline
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