Child Maintenance Variation Calculator

A CMS variation allows either parent to apply to change the standard maintenance calculation when the basic formula doesn't reflect the true financial position. The paying parent may apply for special expenses to reduce payments; the receiving parent may apply for hidden income or assets to increase payments.

Qualifying special expenses include: travel costs for the paying parent to maintain contact with the child (e.g., petrol, trains, flights — but only if 'on top of' normal travel and above a threshold), boarding school fees paid by the paying parent, and some pre-assessment debt repayments. Not all travel costs qualify — CMS applies specific tests.

Contact travel expenses must be at least £10 per week (£520/year) before a variation can be claimed. The CMS will also assess whether the travel costs are reasonable given the circumstances. Costs must be costs incurred to see the child, not general commuting.

If the paying parent has capital assets (excluding their main home) worth more than £31,250, the receiving parent can apply for a variation treating the assets as generating 8% annual deemed income. This is added to the paying parent's gross income for maintenance purposes. Property, savings, investments, and business assets can all be included.

CMS can request information from HMRC about income (with consent). For variations involving business income, company assets, or complex arrangements, CMS has legal powers to require financial information from the paying parent and third parties. Failure to cooperate can result in a default maintenance decision.

This applies when the paying parent has artificially reduced their declared income by structuring payments through a company (taking low salary, leaving profits in company), paying excessive expenses to connected parties, or other arrangements. CMS can look behind the declared income to the underlying financial benefit.

CMS variation applications typically take 8-12 weeks to process. Complex financial cases (diversion of income, assets) can take considerably longer — sometimes over a year if financial disclosure is contested. During this time, the standard maintenance continues at the current rate.

Variations can only be applied from the date CMS accepts the application — they are not backdated to when the grounds first arose. This means prompt application is important. Changes to income that result in a standard reassessment (not variation) can be backdated to the annual review date.