Thank you for visiting the CMSAS Limited website. Please note, we are NOT the Child Maintenance Service (CMS). If you need to contact the CMS, the number for an existing case with the CMS is 0800 171 2345 and for a new case is 0800 988 0988 or you can go to their website here: CMSAS Limited consultants are specialists in the Statutory Scheme of child support, as administered by the Child Maintenance Service. We would like to make you aware that we are not the Child Maintenance Service (CMS). We are a private company that provide a chargeable service of support, guidance and advice to both Receiving and Paying Parents, with Child Maintenance issues, assessments, appeals, tribunals and all Child Maintenance matters pertaining to the CMS (Child Maintenance Service) and/or HMCTS (Her Majesty’s Courts and Tribunals Service), including where difficulties develop with the CMS and/or HMCTS.

CMS Calculation Example: Basic Rate

The Rates of Child Support and Qualifying & Relevant Children pages help to explain the parameters used for Child Support calculation.

There is a free online calculator, however, please be aware this is a very basic calculator. We can help with more advanced calculations, such as other children resident in your home (as an NRP), etc., as demonstrated below. Alternatively, if you think you have been assessed incorrectly, request a consultation with us, by clicking Request a Consultation.

Basic Rate Example

Matthew, the non-resident parent (NRP) is due to pay Child Support to Lucy, the resident parent (RP) for two qualifying children, Ben & Ellie. Matthew lives with his new partner, Joanna, and their baby Jude. Jude is a relevant other child.

Matthew’s gross income is £650 per week. The basic rate of child support applies.

There is one relevant other child (Jude) so this is reduced by 11%.

Step One:

Gross Weekly income = £650

There is 11% reduction as there is one relevant other child = £71.50

Gross weekly income after the reduction for relevant other children = £578.50

Income between £0 and £800 = £578.50

Step Two:

There are two qualifying children, so child support is 16% of £578.50.

16% of £578.50 = £92.56

Matthew is due to pay £92.56 child support per week to Lucy.

If you would like to arrange an initial consultation with us, please click here to talk to us.

Basic rate; reduction in gross income for relevant other children

Number of relevant other childrenPercentage by which gross income is reduced

Basic rate; percentages used to calculate Child Support payable are shown below:

Number of
qualifying children (including
relevant non-resident children)
Percentage of
gross income
up to £800
Percentage of
gross income
above £800
Three or more19%15%

Further examples of calculations can be found by clicking here.

If you would like to arrange an initial consultation with us, please click here or select one of the options below.

Initial Consultation

We charge £175 (£210 inc. VAT) for an initial consultation.

Additional Consulting Hours

We charge £150 (£180 inc. VAT) for additional hours.

Father and baby daughter