CMS Shared Care Nights Calculator
Calculate how overnight contact nights reduce Child Maintenance Service (CMS) payments. The shared care reduction applies when the non-resident parent has the child overnight 52 or more nights per year.
Frequently Asked Questions
What is the CMS shared care reduction?
When the non-resident parent (NRP) has the child overnight, the CMS reduces the weekly maintenance payment. The reduction applies in bands based on the number of overnight nights per year: 52-103 nights = 1/7 reduction, 104-155 = 2/7, 156-175 = 3/7.
What counts as an overnight for CMS purposes?
An overnight is when the child sleeps at the non-resident parent's home. Day visits do not count. The nights must be with the non-resident parent (the one paying maintenance), not with other relatives or childminders. Evidence of overnights may be required if disputed.
What is the threshold for shared care reduction?
The minimum is 52 overnights per year (approximately 1 per week). Below 52 nights, no shared care reduction applies. If the child spends equal time with both parents (around 182+ nights each), different CMS rules apply — you may be in the 'equal shared care' situation.
How does CMS calculate income?
CMS uses gross annual income from HMRC as the basis for calculation. For employed parents, this is gross employment income (before tax and NIC). Self-employed parents use their net profit. The weekly figure is annual income divided by 52. CMS can request income from HMRC directly.
What is the deduction for other children?
If the paying parent has other children living with them (relevant other children in the household), their income is adjusted downwards. The deduction is 11% for 1 child, 14% for 2, and 16% for 3+. These children can be biological, adopted, or under a child arrangements order.
Can the CMS amount be varied?
Yes — the paying parent can request a variation in CMS if: they have special expenses (e.g., travel for contact), they have assets above £31,250, they have income not in the HMRC figure (e.g., dividends, rental income), or the receiving parent is staying in a home paid for by the paying parent.
Is CMS calculated on gross or net income?
CMS uses gross income (before income tax and NIC). This differs from the old Child Support Agency formula which used net income. The gross basis means the actual percentage of take-home pay going to child maintenance is effectively less than the headline rate suggests.
What if the paying parent is self-employed?
For self-employed parents, CMS uses net profit from the most recent HMRC tax calculation. If the self-employed parent can manipulate their declared profit, CMS may challenge this via a variation request citing 'unearned income' or 'diversion of income'. Significant assets (above £31,250) can also be taken into account.