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 Plus

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.

CMS Calculation using Basic Rate Plus

Scott, the non-resident parent (NRP) is due to pay Child Support to Isabelle, the resident parent (RP) for two qualifying children. Scott lives with his new partner, Tanya, and they have no children together.

Scott is a company director, and pays himself a salary and dividends. His salary is kept below the Lower Earnings Limit (LEL) where employees do not pay National Insurance but get the benefits of paying. In 2020/2021 this is £120 per week. He then takes dividends throughout the year, totalling £36,400 which equates to £700 per week.

Scott’s gross income is £820 per week. The ‘basic rate plus’ of child support applies because his gross weekly income is over £800 per week.

Step One:

Gross weekly income = £820

There is no percentage reduction as there are no relevant other children.

Income between £0 and £800 = £800

Income over £800 = £20

Step Two:

There are two qualifying children, so child support is 16% of £800 plus 12% of the excess above £800 (£20 in this example).

16% of £800 = £128

12% of £20 = £2.40

£128 + £2.40 = £130.40

Scott is due to pay £130.40 child support per week to Isabelle.

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.

African father and son