Child maintenance repayment planner

Child Maintenance Arrears Calculator

Estimate how long child maintenance arrears could take to clear, how much remains after 12 months, and what monthly arrears payment would be needed for a target date.

Enter The Arrears Plan

Current balance Arrears balance Use the balance from the CMS statement or written agreement. £ Lump sum paid now Optional payment before monthly arrears repayments start. £

Monthly payments Ongoing maintenance due each month Current maintenance is separate from arrears. £/mo Proposed arrears repayment Amount paid toward old arrears each month. £/mo Affordable total monthly payment Optional budget line for ongoing maintenance plus arrears. £/mo

Target and missed payments Target months to clear arrears Use this to compare your proposed repayment with a target timescale. months Expected missed ongoing payments in next year Add missed current maintenance if you want to stress-test the balance. months Admin or collection fee allowance Optional monthly amount if the arrangement has extra costs. Leave at 0 if not used. £/mo

Arrears Timeline

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Enter the balance and repayment to see the estimated timeline.

Next 12 Months

This does not change a CMS decision, court order or written payment arrangement. Use it to prepare questions and compare dates.

What This Arrears Calculator Does

Child maintenance arrears are missed or underpaid child maintenance amounts from earlier periods. They are separate from the current monthly maintenance that may still be due. This calculator is a repayment planner: it estimates how long an arrears balance could take to clear at a proposed monthly amount, what the balance might look like after 12 months, and what arrears payment would be needed to clear the balance by a target month.

It is not a Child Maintenance Service liability calculator. It does not decide income, shared care, qualifying children, special expenses, variation grounds, Collect and Pay action, enforcement, write-off policy or court steps. The safest source for the balance is a CMS statement, court order, written agreement or formal schedule. If the balance is disputed, use the calculator only for scenarios while asking for the official calculation history.

Current Maintenance Comes First

A repayment plan can look affordable only because it ignores current maintenance. The tool therefore shows ongoing maintenance and arrears repayment as a combined monthly amount. If the paying parent pays old arrears but misses current maintenance, the total debt may not fall. The missed-payment stress field lets you add future missed current maintenance to the arrears balance so both parents can see the risk in plain numbers.

If payment is through CMS Collect and Pay, extra collection charges may apply under the CMS rules. This calculator leaves any fee allowance editable because arrangements differ and rates can change. Enter a monthly amount only when it is shown on your CMS paperwork or you are testing a scenario.

Formula And Method

Starting arrears after lump sum = arrears balance - lump sum Months to clear = starting arrears / monthly arrears repayment, rounded up Balance after 12 months = starting arrears - 12 x repayment + missed current maintenance Target repayment = starting arrears / target months

The calculator assumes monthly payments are made on time and that no official reassessment changes the arrears balance. It does not add interest by default. It rounds the months to clear up to a whole month because a part-month remaining balance still needs paying. Where a repayment would clear the arrears before 12 months, the 12-month balance is shown as zero unless missed ongoing maintenance is added.

Worked Arrears Examples

Steady monthly plan

Arrears of GBP 1,800 with a GBP 200 lump sum leave GBP 1,600. Paying GBP 120 a month clears that balance in about 14 months, provided current maintenance is also paid.

Target 12-month plan

If the remaining arrears are GBP 1,600 and the target is 12 months, the arrears payment needs to be about GBP 133.34 a month. Add current maintenance to see the full monthly cash commitment.

Missed current maintenance

If two current monthly payments of GBP 260 are missed during the year, GBP 520 is added back into the debt position. A repayment plan that looked on track can slip quickly.

Arrears Action Checklist

Step	Why it matters	What to keep
Ask for the official balance	Arrears can come from missed payments, reassessments or collection timing.	CMS statement, calculation schedule and payment history.
Separate ongoing maintenance	Current maintenance must usually continue while arrears are repaid.	Monthly liability notice or agreement.
Record every payment	Bank records reduce disputes about dates and amounts.	Bank statements, payment references and receipts.
Check affordability	An unrealistic repayment may fail and lead to more arrears.	Budget sheet, wage slips and priority bills.
Act early if payments stop	CMS has routes for missed payments and enforcement where a case is open.	Messages, missed-payment dates and contact notes.

When CMS Or Legal Help Matters

Use official help if the arrears balance is disputed, if the paying parent has changed income, if payments are being made outside the recorded route, if deductions from earnings are being considered, if there are enforcement steps, or if a family-based arrangement is breaking down. Citizens Advice and GOV.UK explain that child maintenance can involve service rules, fees, collection methods and enforcement powers. A private spreadsheet cannot replace those routes.

For Receiving And Paying Parents

Receiving parents often need a clear timeline because arrears affect household budgeting for the child. Paying parents often need to test what can be paid without missing current maintenance and priority bills. Both sides benefit from separating three lines: current maintenance, old arrears, and any extra fees or costs. If communication is difficult, keep the calculation factual and share the source balance, proposed payment, target date and review date.

FAQs

Can this calculator reduce child maintenance arrears?

No. It only estimates a repayment timeline. Any official change must come through the CMS, a court route or the relevant written agreement.

Should current maintenance be paid while arrears are repaid?

Usually yes. Old arrears and current maintenance are different. Missing current maintenance can create new arrears even if old debt is being paid.

What if the arrears balance is wrong?

Ask for a breakdown, payment history and calculation record. Do not rely on a planner until the starting balance is checked.

Can CMS take enforcement action for arrears?

GOV.UK explains that CMS can take action when child maintenance is not paid. The route depends on the case and collection method.

Is this legal advice?

No. It is a planning calculator. Get advice from CMS, Citizens Advice, a solicitor or a debt adviser where enforcement, court action, affordability or disputed liability is involved.

Sources

Department for Work and Pensions. (2026). Child maintenance if a paying parent fails to pay. GOV.UK. https://www.gov.uk/child-maintenance-if-paying-parent-fails-to-pay
Department for Work and Pensions. (2026). Manage your Child Maintenance Service case. GOV.UK. https://www.gov.uk/manage-child-maintenance-case
Citizens Advice. (2026). Child maintenance. https://www.citizensadvice.org.uk/family/children-and-young-people/child-maintenance/