Child Maintenance Calculator
The official CMS calculator uses gross income - which most people don't know off the top of their head. Ours uses your net take-home pay, so you instantly see what you'd actually pay or receive.
Child Maintenance Calculator
Enter your gross salary - we calculate tax, NI and your CMS amount
Your salary before tax and NI are deducted - shown on your payslip as "Gross Pay".
Enter the same period as above (e.g. monthly if you selected "per month"). Salary sacrifice only - these are deducted before tax and reduce what the CMS counts as your income. Personal pension payments outside of payroll do not reduce CMS income.
What counts as an overnight stay? (important - read this)
Under Schedule 1, paragraph 7 of the Child Support Act 1991 and Regulation 46 of the Child Support Maintenance Calculation Regulations 2012, a night only counts if:
The child physically sleeps overnight at the paying parent's address.
The CMS counts the total expected nights per 12-month period from the effective date. It will ask for evidence - a court order, agreed schedule, or established pattern.
DOES count
- ✓Child sleeps at the paying parent's home overnight
- ✓Nights during school holidays where the child stays over
- ✓Regular weekly overnight contact (e.g. every other weekend)
- ✓Overnight stays ordered by a court (court order is strong evidence)
- ✓Hospital stays where the paying parent would normally have the child that night
Does NOT count
- ✗Daytime visits, however long - even full days
- ✗Picking up and dropping off without an overnight stay
- ✗Nights the child spends at grandparents' or other relatives
- ✗Staying at a friend's house arranged by the paying parent
- ✗Nights where the child is not at the paying parent's address
How nights reduce your payment (Schedule 1, para. 7, CSA 1991)
| Nights per year | Reduction | What this means |
|---|---|---|
| 0–51 | None | No reduction applied |
| 52–103 | 1/7 deducted | ~1 night/week on average |
| 104–155 | 2/7 deducted | ~2 nights/week on average |
| 156–174 | 3/7 deducted, minus £7/wk | ~3 nights/week on average |
| 175+ | 1/2 deducted, minus £7/wk | Roughly equal care |
If nights are shared across multiple children in the same household, the fractions are averaged. At 156+ nights an additional £7/week is subtracted per qualifying child. If this would reduce the payment below £7/week, the minimum payable is £7/week.
View Regulation 46 (2012 SI) on legislation.gov.ukBased on UK CMS rates and HMRC 2026/27 tax thresholds. For guidance only - not legal advice.