Child Maintenance Calculator 2026 (CMS / CSA)
Estimate weekly, monthly, and annual payments using the official CMS formula — gross income, pension deductions, shared care nights, and all five rate bands.
How Child Maintenance is Calculated in 2026
£2,900
Median annual payment via CMS Collect & Pay (2024/25)
12–19%
Basic Rate — % of gross income depending on child count
6 steps
Official CMS formula from gross income to weekly amount
The Child Maintenance Service uses gross income — your pay before income tax and National Insurance — as the starting point. This is the single biggest difference from the old CSA scheme, which used net income, and the most common source of miscalculation.
1
Establish gross weekly income
Annual salary ÷ 52. The CMS verifies this against HMRC records rather than relying on self-reported figures. If income has changed by more than 25% since the last tax year, you can request a current-year estimate.
2
Deduct pension contributions
Approved pension contributions — workplace and personal — are subtracted from gross income before the rate is applied. A £5,200 annual pension contribution reduces CMS-assessed income by exactly £100/week.
3
Reduce income for other children
If the paying parent supports other children who live with them (Child Benefit in their name), income is reduced: 11% for 1, 14% for 2, 16% for 3 or more other children.
4
Apply the rate band
The adjusted weekly income determines which of five rate bands applies: Nil, Flat, Reduced, Basic, or Basic Plus. Each uses a different calculation method.
5
Apply percentage for number of children
Basic Rate: 12% for 1 child, 16% for 2, 19% for 3 or more. Percentages differ slightly at Reduced and Basic Plus bands.
6
Apply shared care reduction
52–103 overnight stays: 1/7th off. 104–155 nights: 2/7ths off. 156–174: 3/7ths off. 175+: half off. Below 52 nights, no reduction applies.
CMS Rate Bands Explained: All Five Tiers
Your adjusted weekly income (after pension and other-children deductions) determines which band applies. Most cases fall into the Basic Rate — but the edges of each band carry large financial consequences.
| Rate band | Adjusted weekly income | How it works | Weekly (1 child) |
|---|---|---|---|
| Nil | Under £7/wk | No maintenance payable. Also applies to full-time students, those in prison, and certain benefit recipients. | £0.00 |
| Flat | £7–£99.99/wk | Fixed £7/week (1 child), £25 (2 children), £50 (3+). Applies to benefit claimants. | £7.00 |
| Reduced | £100–£199.99/wk | Blended: interpolates between £7 and the full Basic Rate amount across the £100–£200 range. | £7–£24 |
| Basic | £200–£3,000/wk | 12% (1 child), 16% (2), 19% (3+) of adjusted weekly income. Covers the vast majority of cases. | £24–£360 |
| Basic+ | Over £3,000/wk | Basic rate up to £3,000/wk, then 9%/12%/15% on the next £800/wk. Receiving parent must go to court above £3,800/wk. | £360 + up to £72 |
Earners above £156,000/year hit the Basic Plus cap. At £3,800/week adjusted income, the CMS-calculated amount for one child reaches its ceiling of approximately £432/week. Above that, the receiving parent must apply to the Family Court for a top-up order.
| Children paid for | Basic Rate % | Basic Plus % (income above £3,000/wk) |
|---|---|---|
| 1 child | 12% | 9% |
| 2 children | 16% | 12% |
| 3 or more | 19% | 15% |
Three Realistic Scenarios: What Parents Actually Pay
Scenario A — Average earner, one child, no shared care
Gross income: £35,000/year. No pension. No other children. Child stays 30 nights/year.
Gross weekly income£673.08
Rate bandBasic (12%)
Weekly maintenance£80.77
Shared care reductionNone (under 52 nights)
Final weekly payment£80.77
Annual equivalent£4,200/year
Scenario B — Pension contributions cut the bill significantly
Same £35,000 earner but pays £5,200/year (10%) into a workplace pension. No other children. 1 child.
Gross weekly income£673.08
Pension deduction (£5,200 ÷ 52)−£100.00
Adjusted weekly income£573.08
Basic Rate (12%)£68.77
Final weekly payment£68.77
Annual saving vs Scenario A£624 less per year
Scenario C — High earner, two children, significant shared care
Gross: £80,000/year. 2 children in maintenance arrangement. 1 other child lives with paying parent. Children stay 130 nights/year.
Gross weekly income£1,538.46
Other-child adjustment (11%)−£169.23
Adjusted weekly income£1,369.23
Basic Rate 2 children (16%)£219.08
Shared care 2/7ths (104–155 nights)−£62.59
Final weekly payment£156.49
Annual equivalent£8,137/year
The difference between 104 and 155 overnight stays is a full 2/7ths reduction — worth over £3,000/year at average earnings. If arrangements hover near 100 nights, even modest increases in overnight stays can shift you into a significantly cheaper band. Keep a written log.
Child Maintenance and Pension Contributions
Pension contributions are one of the very few deductions that legally reduce the income figure the CMS uses. This is widely misunderstood — and one of the most-searched subtopics in child maintenance.
Workplace pension (auto-enrolment)
Both employee and employer contributions count. If you pay 5% and your employer adds 3%, the full 8% on qualifying earnings reduces the CMS income figure. Evidence via payslips.
Personal pension / SIPP contributions
Regular contributions into a SIPP or personal pension are deductible. You must evidence these to the CMS via pension statements or bank records showing regular transfers.
What is NOT deductible
Past pension arrears, ISAs, stocks, savings accounts, and one-off transfers are not accepted. The CMS will reject unsubstantiated or inconsistent claims. Inflated pension contributions specifically to reduce maintenance may trigger a departure direction.
Pension contribution impact on weekly maintenance (£40,000 gross, 1 child)
| Annual pension | Adjusted weekly income | Weekly maintenance | Annual saving |
|---|---|---|---|
| £0 | £769.23 | £92.31 | — |
| £2,000 (5%) | £730.77 | £87.69 | £240/year less |
| £4,000 (10%) | £692.31 | £83.08 | £480/year less |
| £8,000 (20%) | £615.38 | £73.85 | £960/year less |
| £16,000 (40%) | £461.54 | £55.38 | £1,920/year less |
Self-Employed Child Maintenance Calculator: How CMS Treats Your Income
Self-employed income is the most contested area in maintenance calculations. The CMS uses gross profit from HMRC self-assessment records — turnover minus allowable business expenses — not drawings or dividends taken.
HMRC data source
Previous tax year
CMS uses your most recent filed self-assessment. If income changed more than 25%, apply for a current-year variation.
Fluctuating income
Annual review
Unlike PAYE (updated via HMRC RTI), self-employed income is reviewed at self-assessment date. Notify CMS of major interim changes.
Director-shareholders
Dividends counted
If you take dividends from a limited company, the CMS can include these. The receiving parent may apply for an "unearned income" variation if declared income seems low.
Lifestyle variation
Available to both
If the paying parent's lifestyle does not match their declared income — e.g. using company assets personally — the receiving parent can apply for a lifestyle variation.
Shared Care Reductions: The Exact Fractions
Shared care is the second most impactful variable after income. The reductions are applied as exact fractions of a seven-day week, not rounded percentages.
| Nights per year | Approx per week | Reduction | % off | Impact at £100/wk base |
|---|---|---|---|---|
| 0–51 | Under 1 | None | 0% | £100.00/wk |
| 52–103 | ~1 night | 1/7th | 14.3% | £85.71/wk |
| 104–155 | ~2 nights | 2/7ths | 28.6% | £71.43/wk |
| 156–174 | ~3 nights | 3/7ths | 42.9% | £57.14/wk |
| 175+ | ~Equal | 1/2 | 50% | £50.00/wk |
Equal shared care (175+ nights) halves the amount — but does not result in zero maintenance. The higher-earning parent continues to pay a reduced amount to the lower earner. The common assumption that 50/50 care eliminates maintenance is incorrect.
Crossing from 51 to 52 nights per year is the single largest threshold — it triggers a 1/7th deduction. At £35,000 gross income, this is worth approximately £600/year. Keep a calendar log of every overnight stay and submit evidence to the CMS if the threshold is disputed.
CMS, Private Arrangement, or Court Order — Which Route?
Family arrangement
No fees
Parents agree directly — no government involvement, no collection fees, no enforcement. Works where communication is functional. Cannot be enforced without CMS or court.
CMS Direct Pay
£20 setup
CMS calculates the amount; paying parent transfers directly. No collection fee. Enforcement requires escalation back to CMS if payments stop.
CMS Collect & Pay
+20% surcharge
CMS collects from the paying parent and pays to the receiving parent. Paying parent pays 20% extra; receiving parent receives 4% less. Total impact: 24% above the base amount.
Court consent order
12 months only
Binding for 12 months, after which either parent can open a CMS case regardless. Rarely produces different figures from the CMS formula. Used mainly for complex asset situations.
| Your situation | Best route | Why |
|---|---|---|
| Cooperative co-parenting, stable income | Family arrangement | Zero cost; use this calculator to set a fair figure. |
| Some tension but payments made voluntarily | CMS Direct Pay | Formal CMS figure, no fees, formal record. |
| Repeated missed payments or evasion | CMS Collect & Pay | CMS enforces and transfers. 24% surcharge is the cost of reliability. |
| Income above £156,000/year | CMS + court top-up | CMS caps at £3,800/wk adjusted income; court orders higher amounts. |
| Self-employed with disputed income | CMS with variation | Receiving parent can request lifestyle variation. CMS can investigate. |
Child Maintenance 2025 vs 2026: What Changed
The CMS percentage rates themselves have not changed since 2012. What changes annually is the HMRC income data the CMS uses — updated each April to reflect the most recently filed tax year.
| Factor | 2025 | 2026 | Impact |
|---|---|---|---|
| CMS percentage rates | Unchanged | Unchanged | Formula stays the same |
| HMRC income data year | 2022/23 | 2023/24 | Income growth is automatically captured — maintenance rises if earnings increased |
| Nil Rate threshold | Under £7/wk | Under £7/wk | No change |
| Flat Rate threshold | £7–£100/wk | £7–£100/wk | No change |
| Shared care thresholds | 52/104/156/175 nights | 52/104/156/175 nights | No change |
| CMS application fee | £20 (DV waiver) | £20 (DV waiver) | No change |
| Collect & Pay surcharge | 20% / 4% | 20% / 4% | No change |
The practical implication for 2026: if the paying parent's income grew between 2022/23 and 2023/24 (what HMRC now holds), their maintenance obligation increases automatically at the next review — with no action required by either party. Conversely, a significant income drop in 2023/24 will reduce the obligation, but only if the self-assessment or RTI data accurately reflects it.
Common Mistakes That Distort the Maintenance Assessment
!
Using net (take-home) pay instead of gross income
The CMS uses gross income — before income tax and NI. Using take-home pay as the starting figure gives a significantly lower result and leads to disputes when the CMS produces its own calculation from HMRC records.
!
Miscounting overnight stays
Only nights the child actually sleeps at the paying parent's home qualify. Daytime contact, school pickups, and holidays where the child returns the same evening do not count. Missing the 52-night threshold by just a few nights costs approximately £600/year at average earnings.
!
Assuming a private agreement is enforceable
An informal written agreement cannot be enforced if the paying parent stops paying. Only a CMS case or court order provides enforcement tools. Either parent can open a CMS case at any time, overriding any private arrangement.
!
Forgetting that equal shared care does not mean zero maintenance
175+ nights per year triggers a 50% reduction — not elimination. The higher earner still pays a halved amount to the lower-earning parent in most cases.
✓
Act early and contact Citizens Advice before disputes escalate
Court proceedings for maintenance are expensive and slow. The CMS handles the majority of disputes faster and at lower cost. Free advice: Citizens Advice or CMS helpline 0800 171 2345.
Frequently Asked Questions
How much child maintenance should I pay in 2026?
At the Basic Rate with one child, 12% of your adjusted gross weekly income. At £35,000 gross income with no pension deductions and no shared care, that is approximately £80.77/week (£4,200/year). Two children: 16% (£107.69/week). Three or more: 19% (£127.88/week). Use the calculator above for your specific circumstances including pension and shared care adjustments.
What is the difference between the CMS calculator and the old CSA calculator?
The CSA was replaced by CMS in 2012. The critical difference: CSA used net income (after tax and NI), whereas CMS uses gross income (before tax and NI). This makes CMS-assessed maintenance consistently higher for the same take-home pay. All CSA cases should have migrated to CMS. If you see references to a "CSA calculator," they are describing what is now the CMS formula.
Does child maintenance include pension contributions?
Yes — pension contributions are deducted from gross income before the CMS rate is applied. This covers workplace pensions (employee and employer contributions) and personal pensions or SIPPs. At £40,000 gross income, a 10% pension contribution reduces the annual maintenance bill by approximately £480 for one child. The CMS requires evidence of contributions — payslips or pension statements.
How does the self-employed child maintenance calculator work?
For self-employed parents, the CMS uses gross profit (turnover minus allowable business expenses) from the most recent HMRC self-assessment return. Limited company directors may also have dividends included. Our calculator above uses income as entered — for self-employed parents, enter your gross profit figure (not turnover). The CMS can apply a variation if declared income appears inconsistent with lifestyle.
What happens if the paying parent refuses to pay?
With a CMS case, enforcement powers include deductions from wages (via the employer), deductions from bank accounts, removal of driving licences, charging orders on property, and in serious cases imprisonment. Enforcement is only available through CMS Collect & Pay. Direct Pay cases must be escalated to enforcement mode first, which converts the case to Collect & Pay.
Does child maintenance affect Universal Credit?
No. Child maintenance received is fully disregarded for Universal Credit — it does not reduce your UC award. Similarly, maintenance paid out by the paying parent does not reduce their UC. Both parents can claim UC regardless of any maintenance arrangement. This has been the rule since April 2010 and remains unchanged in 2026.
What is the maintenance assessment fee?
The CMS charges a one-off £20 application fee to open a case. This is waived for victims of domestic violence and for applicants under 19. Beyond the application fee, charges only apply with Collect & Pay: the paying parent pays 20% above the calculated amount; the receiving parent receives 4% less. There is no ongoing fee with Direct Pay or a family arrangement.
Can I agree child maintenance privately without the CMS?
Yes. A family-based arrangement has no fees and no government involvement. Many parents use a calculator like this to agree a figure and put it in writing. The key limitation: it cannot be enforced without returning to CMS or going to court. Either parent can apply to CMS at any time, and the CMS calculation will override any private figure if there is a dispute.
Disclaimer: This calculator provides an estimate based on the standard CMS formula. Actual maintenance assessed by the CMS will use HMRC income records and may differ from your entered figures. For free advice, contact Citizens Advice or the CMS on 0800 171 2345.