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.
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Who this applies to
- All Isle of Man employers with employees earning above the National Insurance lower earnings limit (£129 per week or £559 per month for 2026/27)
- Directors of Isle of Man companies receiving a salary through ITIP
What to file
The monthly remittance card (Form T35) showing the ITIP and National Insurance deducted for the income tax month, filed even if the amount is nil. At the end of the tax year the employer's annual return (Forms T37, T14 and T9) is due within 30 days after 5 April, which is by 5 May.
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
A late monthly payment carries a penalty of 5% of the amount due, and a further 5% if it remains outstanding after six months. A late annual return carries a penalty of £250 plus £50 per day until it is submitted. 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 Isle of Man rates of 10% and 21% above the personal allowance (£17,000 for 2026/27)
- Deduct employee NICs at 11% between the primary threshold and the upper earnings limit, and 1% above it
- Calculate employer NICs (12.8% above the secondary threshold of £176 per week)
- Submit the monthly remittance card 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
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