How CMS Calculates Child Maintenance

 How CMS Calculates Child Maintenance:

The CMS uses a straightforward formula to determine payments. Here's a breakdown: Gross Weekly Income: The paying parent's gross weekly income is divided into bands. Income Bands: Up to £100 or if on benefits: Flat rate of £7 per week. £100.01 to £199.99: Reduced rate. £200 to £800: Basic rate. £800.01 to £3,000: Basic plus rate. Percentage Based on Number of Children: One child: 12% of gross weekly income. Two children: 16% of gross weekly income. Three or more children: 19% of gross weekly income. Shared Care Reduction: The amount is reduced if children spend a certain number of nights per year with the paying parent: *Shared Care Bands* Band A 52 to 103 nights: 1/7th reduction. Band B 104 to 155 nights: 2/7th reduction. Band C 156 to 174 nights: 3/7th reduction. Band Equal 175 or more nights: 50% reduction plus an additional £7 reduction. Example Calculation: Gross Weekly Income: £600 Number of Children: 2 Shared Care: 104 nights per year Calculation: Basic rate for two children: 16% of £600 = £96 Reduction for shared care: £96 - (£96 * 2/7) = £68.57 Final weekly payment: Approximately £68.57 Additional Factors Considered by CMS: Additional Income: Bonuses or overtime pay can affect payment calculations. Other Children: If the paying parent has other children, their taxable income used for calculations is adjusted. One other child: Income reduced by 11%. Two other children: Income reduced by 14%. Three or more other children: Income reduced by 16%. Unemployment and Benefits: If the paying parent is out of work and claiming Universal Credit, they typically pay £1 per day, amounting to £7 weekly. *Pension Contributions:* Pension contributions can also reduce the income considered for child maintenance calculations. Using the CMS ensures that child maintenance payments are calculated fairly and enforced legally. Understanding how these calculations work can help both paying and receiving parents manage expectations and plan accordingly.

CMS Mileage Claims Explained (2026): Child Maintenance, Fuel Rates and Contact Costs

CMS Mileage Claims Explained (2026)

How contact costs, fuel rates and Child Maintenance Service rules affect paying parents in England, Wales and Scotland

If you are a paying parent and you regularly travel to see your child, the Child Maintenance Service (CMS) may be able to take some of those travel costs into account.

The key point is this: CMS does not pay you mileage back in cash, and it does not use the standard 45p per mile business mileage rate that many people know from work expenses. Instead, travel for contact can be treated as a special expense, which may reduce the income figure CMS uses when calculating child maintenance.

This guide explains how CMS mileage claims work, who can claim, the current advisory fuel rates, and what evidence can help if you apply.

Who can claim mileage through CMS?

Only the paying parent can claim mileage as a contact cost through CMS.

This is one of the most common points of confusion. The receiving parent cannot use this special-expenses route to claim mileage.

Older guidance and articles often refer to the “resident parent” and “non-resident parent”. More recent language usually uses receiving parent and paying parent, but the practical point stays the same: the mileage rule only applies to the paying parent who is incurring contact costs.

What counts as a contact cost?

Mileage is only one part of contact costs.

Where the facts support it, CMS may also look at things such as:

• public transport fares
• taxi fares in limited situations, for example where disability or long-term illness makes other travel impracticable
• car hire where it is cheaper overall
• overnight accommodation where a same-day return is impracticable or contact takes place over consecutive days
• some tolls, bridge charges and road charges
• in some cases, the cost of a necessary third party travelling with the paying parent or child

That said, not every motoring cost counts. The guidance is about fuel for contact journeys, not wider running costs such as insurance, servicing, tyres or depreciation.

CMS does not use 45p per mile

Many parents assume CMS uses the standard 45p per mile HMRC business mileage rate. It does not.

Instead, CMS uses HMRC advisory fuel rates when looking at fuel costs for contact journeys. These rates change during the year and vary depending on vehicle type, engine size, and in the case of electric vehicles, the charging method.

This means the amount allowed for mileage can be much lower than many people expect.

Current HMRC advisory fuel rates used in CMS mileage cases

Below are the current advisory fuel rates used for this article.

HMRC advisory fuel rates from 1 March 2026

Fuel type	Vehicle / charging category	Rate per mile	Miles needed to reach £10 a week
Petrol	1400cc or less	12p	About 84 miles
Petrol	1401cc to 2000cc	14p	About 72 miles
Petrol	Over 2000cc	22p	About 46 miles
Diesel	1600cc or less	12p	About 84 miles
Diesel	1601cc to 2000cc	13p	About 77 miles
Diesel	Over 2000cc	18p	About 56 miles
LPG	1400cc or less	10p	About 100 miles
LPG	1401cc to 2000cc	12p	About 84 miles
LPG	Over 2000cc	19p	About 53 miles
Electric	Home charging	7p	About 143 miles
Electric	Public charging	15p	About 67 miles

Hybrid vehicles are generally treated as either petrol or diesel for advisory fuel rate purposes.

Why the £10 weekly threshold matters

The £10 weekly threshold is important.

If your contact costs do not reach at least £10 a week, the variation is unlikely to help. This is why some parents technically qualify for mileage in principle, but still see no practical benefit.

For example:

• a home-charged electric car at 7p per mile would need around 143 miles a week to reach £10
• a petrol car over 2000cc at 22p per mile would need around 46 miles a week to reach £10

Before you apply, it is worth working out your usual weekly contact mileage so you can see whether you are realistically over the threshold.

How a mileage claim affects child maintenance

A successful mileage claim does not mean CMS sends you money for fuel.

Instead, if CMS accepts the contact cost as a special expense, the approved weekly amount is usually deducted from the paying parent’s gross weekly income before child maintenance is recalculated.

So if CMS allows £20 a week in contact costs, it does not refund £20. It reduces the income figure used in the formula, and the maintenance calculation is then worked out again.

In practice, the actual saving depends on things such as:

• the paying parent’s gross weekly income
• the number of qualifying children
• whether there are any relevant other children in the paying parent’s household
• shared care arrangements
• whether any other adjustments apply

This is why a mileage claim can sound significant on paper but still lead to only a modest reduction in the weekly maintenance amount.

What evidence helps with a CMS mileage claim?

Good evidence matters.

If you are applying for a contact costs variation, keep your records clear and consistent. Helpful evidence can include:

• a mileage log
• dates of contact
• start and end postcodes
• the vehicle’s fuel type and engine size
• receipts or other records supporting the journeys
• toll, parking or accommodation records where relevant

A simple weekly log is often much more effective than loose receipts with no explanation.

It is also sensible to make sure the journey being claimed is clearly linked to contact with your child. Keeping your records organised from the start can make the application easier to follow and strengthen your case.

Practical tips if you are planning to apply

If you are a paying parent thinking about a claim, these points can help:

1. Work out the numbers first

Before applying, calculate your average weekly contact mileage using the correct advisory fuel rate for your vehicle.

2. Keep a regular record

If your contact pattern is weekly, fortnightly or during school holidays, log it carefully so the pattern is easy to understand.

3. Record the right journey

The strongest claims clearly show that the travel is for contact with the child.

4. Keep supporting documents

Receipts, booking confirmations and toll records can all help where they support the journey pattern.

5. Be realistic about the result

Even if your claim is accepted, the reduction in maintenance may be smaller than expected.

How to apply for a CMS variation

You can ask CMS to consider a variation when you first apply for child maintenance or after a calculation is already in place.

If you are relying on contact costs, gather your evidence before or while making the request so you can explain:

• the contact pattern
• the journeys involved
• how often they happen
• the weekly cost
• why the costs are necessary

CMS can take time to review a variation, so it helps to keep ongoing records rather than trying to rebuild the history later.

What if CMS says no?

If CMS refuses the variation, or allows less than you think is correct, you can ask for a mandatory reconsideration.

This means CMS looks at the decision again.

If the outcome still seems wrong after mandatory reconsideration, you may be able to appeal to the tribunal. Deadlines usually apply, so it is important to act promptly and keep copies of your paperwork.

Frequently asked questions about CMS mileage claims

Can the receiving parent claim mileage from CMS?

No. Only the paying parent can claim mileage as a contact cost through this special-expenses route.

Does CMS use 45p per mile?

No. CMS uses HMRC advisory fuel rates, not the 45p per mile business mileage rate.

Can electric car drivers claim contact costs?

Yes. Electric vehicle drivers can still claim contact costs, but the advisory rate is much lower than many parents expect. The charging method can also affect the rate used.

Do I need regular contact to claim?

Regular contact makes this type of application much stronger. One-off or occasional trips are much less likely to fit the contact-cost rules in a useful way.

Can tolls or overnight stays count?

Sometimes, yes. Depending on the circumstances, certain tolls, road charges, bridge charges and overnight accommodation may be relevant.

Final word

For most parents, the two biggest misunderstandings are these:

• CMS does not use 45p per mile
• only the paying parent can claim mileage as a contact cost

That matters because many parents overestimate what they can claim, or assume both parents can use the same route.

In reality, CMS contact-cost claims are based on special expenses for the paying parent, and the fuel element is assessed using HMRC advisory fuel rates rather than the standard business mileage allowance.

If you are a paying parent with regular contact and meaningful weekly travel costs, a well-prepared variation request may help reduce your child maintenance calculation. The reduction may not be large, but where the figures genuinely stack up, it can still be worth pursuing.

Private Pensions and Child Maintenance: How Pension Contributions Can Reduce CMS Calculations

If you pay child maintenance, it can be difficult to balance today’s responsibilities with planning for retirement. Even so, pension saving remains important. For many people, the State Pension alone will not be enough, and building up a workplace or private pension can make a real difference later in life.

The good news is that pension contributions can affect the way the Child Maintenance Service (CMS) calculates child maintenance. In many cases, qualifying pension contributions reduce the income figure used in the calculation, which can lower the amount payable.

This article explains how private pensions and workplace pensions are treated by CMS, what evidence you may need to provide, and when CMS may argue that contributions are excessive.

How pension contributions affect child maintenance

CMS usually works out child maintenance using the paying parent’s gross income from HMRC.

However, pension contributions can reduce the income figure used in that calculation.

A simple example:

If you earn £20,000 per year, CMS may initially assess maintenance using that full amount.

If you make £2,000 per year in qualifying pension contributions, the assessable income may reduce to £18,000, which can lower the child maintenance calculation.

This is an important point for parents who want to save for retirement without paying more child maintenance than the rules require.

Regulation 40 and pension deductions

The legal basis for this is found in Regulation 40 of the Child Support Maintenance Calculation Regulations 2012, which deals with pension contributions that are eligible for tax relief at source.

In practical terms, this means that where qualifying private pension contributions have not already been reflected in the HMRC income figure used by CMS, a deduction can be made when the correct evidence is provided.

Workplace pension or private pension: which is easier for CMS purposes?

From a child maintenance point of view, a workplace pension is often easier to manage.

That is because workplace pension deductions are sometimes already reflected in the taxable pay figure reported to HMRC. Where that has already happened, CMS may automatically use the lower income figure without needing any extra adjustment.

However, not all workplace pensions are handled the same way. In some cases, pension contributions are deducted after tax and National Insurance. Where that happens, CMS may still need to make a separate adjustment.

With a private pension, CMS will often see the full income figure first and only make the pension deduction once evidence has been provided.

So while both types of pension can help reduce the income figure used by CMS, a workplace pension is often more straightforward administratively.

What evidence does CMS need?

If you pay into a private pension directly, rather than through payroll, you should normally be ready to provide proof of your contributions.

The best evidence is usually:

• your annual pension statement for the relevant tax year
• confirmation of any tax relief added to the pension
• where relevant, your HMRC tax calculation if you are claiming higher-rate relief

CMS guidance isthat the evidence should match the tax year being used in the child maintenance calculation.  So if your CMS calculation is based on the 25/26 tax year income, only the 25/26 pension contributions reduce the payment.  Not the money you are paying into a pension this year.

As a practical rule, keep all pension statements safely and make sure the figures you send to CMS clearly cover the correct tax year.

You cannot send the pension details before the annual review is complete.  The computer cant see it.  You send afterwards, and they recalculate.

Timing matters: annual reviews and tax years

CMS reviews cases each year using the latest complete tax year available from HMRC.

That means timing matters.

If you want private pension contributions to be taken into account, it is usually best to make sure your evidence clearly relates to the tax year CMS is using for the annual review.

Sending the right evidence for the wrong year can delay things and cause confusion.

Can CMS say pension contributions are excessive?

Yes, sometimes.

Although pension contributions can reduce the income figure used in the standard CMS calculation, CMS can still look more closely at them if there is an argument that the payments are unusually high and are being made to reduce child maintenance rather than genuinely provide for retirement.

Public CMS guidance says there is no fixed deduction cap in the main calculation, but excessive contributions can still become relevant in a variation or diversion of income argument.

The 12% starting point and age-related guidance

CMS guidance has historically used 12% of gross income as a starting point for deciding whether pension contributions appear reasonable.

Above that level, decision-makers may compare contributions with older Financial Services Authority guidance based on the age at which pension saving began.

The guide ranges often referred to are:

• Age 30: 12% to 18%
• Age 35: 16% to 22%
• Age 40: 18% to 25%
• Age 45: 25% to 30%
• Age 50: 30% to 45%
• Age 55: 45% to 70%

These percentages are best understood as guidance, not a hard legal limit.

That matters, because pension rules and individual circumstances vary widely. Someone may have started a pension years ago but contributed too little, taken breaks, or had poor investment growth. So it is not always fair to treat an old start date as a reason to restrict current pension saving, and this could be used to argue a tribunal decision if CMS dont allow the full amount.

Tax rules and CMS rules are not the same

This is a key point that many people miss.

For tax purposes, the standard annual pension allowance is currently £60,000 per year for most people.

But CMS does not automatically accept that any contribution within the tax allowance must also be reasonable for child maintenance purposes.  They are able to do this because a previous case ruled against a paying parent and determined that a maximum level could be set.

So a contribution may be perfectly valid for pension tax relief, while still being challenged by CMS if it looks excessive in the context of maintenance.

Practical tips if you are paying into a pension

If you are paying child maintenance and want your pension contributions to be taken into account properly, these points can help:

Regular contributions are usually easier to explain than one-off lump sums made at the end of the tax year.

Keep your annual pension statements and any HMRC calculations.

Make sure the evidence you send matches the tax year CMS is using.

If you are a higher-rate taxpayer, keep proof of any additional tax relief claimed through HMRC.

If CMS argues that your contributions are excessive, ask for a clear written explanation and consider challenging the decision if the reasoning does not reflect your actual retirement needs.

Important disclaimer

This blog is about child maintenance rules and CMS practice. It is not financial advice or investment advice.

Before making any pension decision, you should do your own research and consider getting independent financial advice.

Frequently Asked Questions

Do pension contributions reduce child maintenance?

They can. CMS guidance says qualifying pension contributions can reduce the gross income figure used in the maintenance calculation.

Does a private pension count for CMS?

Yes. Private pension contributions can be taken into account, but CMS may ask for evidence such as an annual pension statement.

Is a workplace pension better than a private pension for child maintenance purposes?

Not always, but it is often easier administratively because workplace deductions may already be reflected in the income figure supplied to HMRC.

Can CMS refuse to accept pension contributions?

CMS can look closely at contributions if they appear excessive and may consider them as part of a variation or diversion of income argument.

What proof should I send to CMS?

Usually your annual pension statement for the relevant tax year, and where relevant, HMRC documents showing additional tax relief.

Further Information

Child Maintenance - Book available from Amazon.co.uk

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Child Maintenance Regulations Concerning Pension Contributions

This video guide may help:

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