The standard formula looks only at the paying parent’s taxable income. A variation lets either parent ask the CMS to take account of things the formula misses. A paying parent can ask for certain costs to be allowed. A receiving parent can ask for certain extra income to be added.
Special expenses: for the paying parent
The paying parent can ask the CMS to reduce the income used in the calculation because of:
| Expense | What it covers |
|---|---|
| Contact costs | The cost of regular travel to see the child in the calculation, such as fares or fuel |
| Disability or long-term illness | Costs of supporting a child with a disability or long-term illness who lives with the paying parent |
| Prior debts | Some debts taken on for the benefit of the family before the separation |
| Boarding school fees | The maintenance part of boarding school fees for the child in the calculation |
| Mortgage on the former home | Payments on the home the receiving parent and child still live in, if the paying parent no longer has an interest in it |
Each expense must normally be more than £10 a week. The disability and illness expense can have a lower threshold. You cannot get a special expenses variation if your income is below £7 a week.
Contact costs need detail
List each journey: date, from and to, miles or fare, and why. The CMS allows reasonable costs of regular contact. A simple table built from your care diary is ideal.
Additional income: for the receiving parent
The receiving parent can ask the CMS to add income that is not in the standard calculation:
- Unearned income over £2,500 a year, such as rent from property, savings interest and dividends.
- Diverted income, where the paying parent has arranged their affairs to reduce their income for the calculation, for example paying themselves a tiny salary and taking the rest as something else.
- Earnings while on the flat rate, where the paying parent gets a flat rate benefit but also has gross earnings or pension of at least £100 a week.
- Notional income from assets: in some circumstances, the receiving parent can ask for assets worth over £31,250 to be taken into account.
How a variation is decided
- Apply. By phone or in writing to the CMS. Say which ground you are using and give as much evidence and detail as you can.
- The CMS checks it. It may reject it at this stage if it does not meet the basic rules.
- The other parent is told. They usually get a chance to respond and send their own evidence.
- The CMS decides. It must consider whether it is “just and equitable” to agree the variation, looking at all the circumstances.
- The calculation is revised. A variation can take up to three months to come into effect.
You can challenge a variation decision
A decision to agree or refuse a variation is a decision like any other. You can ask for a mandatory reconsideration within one month and then appeal.
Common questions
Can I ask for a variation at any time?
Yes, while the case is open. You can ask with the original application or later.
Will the other parent see my evidence?
They will usually be told about the application and the reasons. If you are worried about specific personal information, tell the CMS and explain why.
My ex owns several rental flats. How do I prove it?
You do not need to prove everything yourself. Give the CMS what you know: addresses, roughly when they were bought, and any listings. The CMS can make its own enquiries.
Sources and law
- Child Support Act 1991, sections 28A to 28G and Schedule 4B (variations)
- SI 2012/2677, Part 5 (variations), including regulations 56, 59, 72 and 73
- GOV.UK: How child maintenance is worked out
