What is the minimum child maintenance amount?

If the paying parent earns less than £100 per week gross (after adjustments), a flat rate of £7 per week applies. If they earn between £100 and £200/week, a reduced rate applies. Income below £100/week results in the flat rate; income above £3,000/week uses the £3,000 cap. The minimum payment is £7/week regardless of earnings below the threshold.

How does shared care reduce child maintenance?

If the paying parent has the children staying overnight for shared care, the maintenance amount is reduced. Reductions are applied in bands: 1–52 nights/year = no reduction; 52–103 nights = 1/7 reduction; 104–155 nights = 2/7 reduction; 156–174 nights = 3/7 reduction; 175+ nights (roughly equal shared care) = 50% reduction plus a further £7/week reduction. Enter your overnight nights in this calculator to see the impact.

What is the difference between CMS and a family-based arrangement?

A family-based arrangement (FBA) is a voluntary agreement between parents without involving the CMS. It is free, flexible, and often more appropriate for amicable separations. The CMS charges a collection fee (2% to the paying parent, 4% deducted from the receiving parent) if it manages payments. FBAs have no fee. The CMS is typically used where parents cannot agree or where there is a history of non-payment.

Can self-employed parents be assessed for child maintenance?

Yes. The CMS uses HMRC data for employed parents, but for self-employed parents it reviews self-assessment tax returns. If the CMS believes the declared income does not reflect the parent's true income, it can request a variation. Parents can also request a variation based on lifestyle inconsistent with declared income, assets, or additional expenses.

What if the paying parent refuses to pay child maintenance?

If a parent refuses to pay, the CMS can use enforcement powers including deduction from earnings orders (DEOs), deduction orders from bank accounts, and, in extreme cases, committal to prison or disqualification from driving. Using the CMS collect and pay service (rather than direct pay) gives access to these enforcement tools, but involves collection fees.

Updated 6 April 2026

Child Maintenance Calculator · Free UK CMS 2026

Estimate child maintenance payments using the Child Maintenance Service (CMS) formula, with shared care night reductions. Updated for 2026.

✓ Free to use✓ CMS formula✓ Shared care reduction✓ Instant results

Child Maintenance Calculator

Enter income, number of children, and shared care nights. The CMS amount appears instantly

Gross weekly income (£)

Number of children

Shared care nights/year

Weekly child maintenance

£60.00

Monthly estimate: £260.00 (× 52 ÷ 12)

Gross weekly income (CMS cap £3,000)

£500.00

Rate

12%

Base weekly maintenance

£60.00

Shared care nights

0 nights/year

Shared care reduction

0.0%

Weekly payment after reduction

£60.00

Monthly estimate

£260.00

Calculated using CMS 3rd scheme formula. The CMS uses HMRC gross income data, enter gross (before tax) weekly income. Actual amounts may differ. This is not legal advice.

How Child Maintenance is Calculated

Quick Answer:CMS child maintenance = paying parent's gross weekly income × percentage rate (12% for 1 child, 16% for 2, 19% for 3+), then reduced for shared care nights. Income is capped at £3,000/week. The flat rate is £7/week for incomes below £100/week.

CMS Rate Table

Number of children	Base rate
1 child	12% of gross weekly income
2 children	16% of gross weekly income
3+ children	19% of gross weekly income

Formula

Weekly maintenance = Gross weekly income × rate% × (1 − shared care reduction)

e.g. £500/week × 16% = £80 (2 children), reduced by 1/7 for 52–103 shared nights = £68.57

Worked Example, £500/week income, 2 children, 104 nights shared care

Gross weekly income£500

Rate (2 children)16%

Base weekly maintenance£80

Shared care nights104 nights (2/7 reduction)

Reduction (2/7)−£22.86

Weekly maintenance£57.14

Monthly maintenance (est.)~£248

The CMS uses the paying parent's gross income as reported to HMRC, not net/take-home pay.

Frequently Asked Questions

The Child Maintenance Service (CMS) calculates child support based on the paying parent's gross weekly income. The base rates are: 12% for 1 child, 16% for 2 children, and 19% for 3 or more children. Income is capped at £3,000 per week (£156,000/year) for CMS purposes. Shared care nights reduce the amount. The CMS uses HMRC income data from the most recent tax year.