Child Maintenance (CMS) Calculator

The Child Maintenance Service (CMS) calculates payments based on the paying parent's gross weekly income. The basic rates are: 12% for one child, 16% for two children and 19% for three or more children. Income is usually sourced directly from HMRC tax data.

The gross income figure is reduced if the paying parent has other children living with them (11% for one, 14% for two, 16% for three or more). Shared overnight care also reduces the amount: one night per week on average reduces the liability by one-seventh.

If income is above £3,532 per week, the reduced rate tiers apply to the portion above this threshold. For very low incomes (below £200/week), a flat rate of £7 per week applies. This calculator follows the CMS formula to estimate weekly and monthly maintenance.

How UK Child Maintenance is calculated. Three methods depending on case: Family-based (private agreement); CMS Direct Pay (CMS calculates, parents arrange payment); CMS Collect & Pay (CMS handles payment, takes 4% fee from receiving parent + 20% from paying parent). CMS uses gross weekly income from HMRC: under £100 = nil rate; £100-£200 = flat £7/week; £200-£800 = basic rate (12% for 1 child, 16% for 2, 19% for 3+); £800-£3,000 = additional 9%/12%/15% on amount above £800; capped at £3,000/week gross.

Adjustments for shared care. Reductions for nights paying parent has child overnight per year: 52-103 nights = 1/7 reduction; 104-155 nights = 2/7; 156-174 nights = 3/7; 175+ nights = ½ reduction (plus £7/week reduction per child). Other children in paying parent's household (including stepchildren): allowance of 11/12/14% reduction for 1/2/3+ other children before main calculation. Example: £500 gross/week, 1 qualifying child, 2 nights/week shared care, no other kids = 12% × £500 = £60/week, minus 1/7 = £51/week.

What counts as income for CMS. Gross weekly income from latest HMRC tax year: PAYE earnings; self-employment profit; pensions; some benefits. Doesn't include: capital (savings, property), unless income generated from them; spouse's income; child benefit. CMS uses 'historic' income (latest tax year) — review request available if income changed 25%+. Unearned income (rental, dividends): £2,500+/year can be included if CMS notified by receiving parent. CMS cannot pursue someone living abroad EU/non-reciprocal countries — REMO scheme covers some Commonwealth and EU.

How long does Child Maintenance last? Until child turns 16, OR 20 if in full-time approved education (A-levels, vocational up to NVQ Level 3 — not degree). Stops if child marries, joins armed forces, or goes to prison. Stops at university entry. Paying parent's death: CMS arrears can be claimed against estate — but ongoing maintenance stops. New child for paying parent: triggers recalculation, reduces existing maintenance. Receiving parent remarrying does NOT stop maintenance from biological father.

Court-ordered maintenance vs CMS. CMS covers up to £3,000/week gross income (£156,000/year). Above that, receiving parent must apply to family court for 'top-up' maintenance. Schools fees, medical, extracurricular: not in CMS calculation — must be agreed privately or via court. Family-based agreements: legally binding only if recorded as a court consent order. Verbal/email agreements: not enforceable but courts give weight. CMS arrears collection: bailiffs, deduction from earnings order, driving licence suspension (up to 2 years), passport seizure, prison (rare but possible).

CMS calculation 2026/27. Gross weekly income from HMRC: under £100 = nil rate; £100-£200 = flat £7/week; £200-£800 = 12%/16%/19% for 1/2/3+ children; £800-£3,000 = additional 9%/12%/15% on excess. Above £3,000/week gross (£156,000/year): CMS caps — apply to family court for 'top-up'. Sample: £500/week gross, 1 child, no shared care = 12% × £500 = £60/week (£3,120/year). Court-ordered alternatives: school fees, medical, holidays — must be agreed privately or via consent order.

Adjustments for shared care. Nights paying parent has child overnight per year: 52-103 nights = 1/7 reduction; 104-155 = 2/7; 156-174 = 3/7; 175+ = ½ reduction (plus £7/week per child). 'Equal time' 175+ nights/year: 50% reduction. Other children in paying parent's household (including stepchildren): 11%/12%/14% reduction for 1/2/3+ other children BEFORE main calc. Sample: £500/week, 1 qualifying child, 2 nights/week (104 nights) shared care = 12% × £500 = £60, minus 2/7 = £43/week.

How long does maintenance last? Until child's 16th birthday OR 20 if in 'approved education' (A-levels, NVQ Level 3, vocational up to NVQ 3). NOT university degrees. NOT apprenticeships paid by employer. Stops if child marries, joins armed forces, or goes to prison. Stops at start of university. Paying parent's death: ongoing maintenance stops; arrears recoverable from estate. New child in paying parent's household: triggers recalculation (typically reduces existing maintenance). Receiving parent remarrying: doesn't affect biological father's maintenance.

Direct Pay vs Collect & Pay. CMS Direct Pay (free): CMS calculates amount, parents arrange payment between themselves. CMS Collect & Pay (with fees): CMS collects and pays — 20% surcharge on paying parent, 4% deduction from receiving parent. Most families use Direct Pay. Collect & Pay needed when: payments unreliable, history of avoidance, abusive ex-partner. CMS enforcement powers: deduction from earnings order, bank account orders, driving licence/passport suspension (up to 2 years), bailiffs, prison (rare but possible).

What CMS doesn't cover — extra costs. School fees (private): not included — agreed privately or via court order. Activities (extracurricular, music, sports): not in CMS. Medical (dental, opticians, private care): not in CMS. Holidays: not in CMS. University maintenance: not in CMS (stops at 19/20 for sixth form). Family-based agreements can cover all these but aren't legally binding unless converted to Court Consent Order (£155 court fee + solicitor £300-£1,500). Many separated parents use family-based agreement for daily plus court order for specific items.