How do I challenge a Child Maintenance Service decision?

If you disagree with a Child Maintenance Service calculation or variation decision, you can request a mandatory reconsideration. This asks the CMS to look at the decision again. You must make this request within one month of receiving the original decision. If the CMS confirms the decision, you may then appeal to the First-tier Tribunal (Social Entitlement) within one month of that confirmation.

What are the time limits for challenging a CMS decision?

You have one month from the date of the original decision to request a mandatory reconsideration. If the CMS confirms the decision after this review, you then have one month from that confirmation to appeal to the First-tier Tribunal (Social Entitlement). Missing these deadlines may prevent you from pursuing the challenge through these specific routes.

What happens if the mandatory reconsideration confirms the CMS decision?

If the mandatory reconsideration confirms the original decision, you can appeal to the First-tier Tribunal (Social Entitlement). The appeal must be lodged within one month of the confirmation. The tribunal hearing is conducted by a panel consisting of a judge and a financial member, and their decision is binding on the Child Maintenance Service.

How long does the child maintenance challenge process take?

The entire process of challenging a Child Maintenance Service decision, including mandatory reconsideration and any subsequent tribunal appeal, typically takes between three and nine months. This timeframe applies to paying or receiving parents who disagree with a CMS calculation or variation decision and wish to pursue the formal challenge journey.

Who decides the appeal and is the decision final?

The tribunal hearing is conducted by a panel that includes a judge and a financial member. The decision made by this tribunal is binding on the Child Maintenance Service, meaning the CMS must follow the tribunal's ruling regarding the maintenance calculation or variation.

All Legal Journeys

Family Law

UK-wide

3 stages

3–9 months

Reviewed 2026-05-22

Child maintenance challenge journey

Challenge a Child Maintenance Service decision through mandatory reconsideration and tribunal appeal.

This page covers UK-wide law. Where local procedure differs (e.g. courts or tribunals), this is noted in the relevant section.

Who Uses This Journey

Paying or receiving parents who disagree with a CMS calculation or variation decision.

Stage-by-Stage Timeline

Mandatory Reconsideration

Request CMS to look again at the decision within 1 month.

Deadline: 1 month from decision

Tribunal appeal

If MR confirms the decision, appeal to the First-tier Tribunal (Social Entitlement) within 1 month.

Forms at This Stage

SSCS1

Hearing

Judge + financial member panel. Decision binding on CMS.

Official Sources

Child Maintenance Service

Frequently asked questions

How do I challenge a Child Maintenance Service decision?: If you disagree with a Child Maintenance Service calculation or variation decision, you can request a mandatory reconsideration. This asks the CMS to look at the decision again. You must make this request within one month of receiving the original decision. If the CMS confirms the decision, you may then appeal to the First-tier Tribunal (Social Entitlement) within one month of that confirmation.
What are the time limits for challenging a CMS decision?: You have one month from the date of the original decision to request a mandatory reconsideration. If the CMS confirms the decision after this review, you then have one month from that confirmation to appeal to the First-tier Tribunal (Social Entitlement). Missing these deadlines may prevent you from pursuing the challenge through these specific routes.
What happens if the mandatory reconsideration confirms the CMS decision?: If the mandatory reconsideration confirms the original decision, you can appeal to the First-tier Tribunal (Social Entitlement). The appeal must be lodged within one month of the confirmation. The tribunal hearing is conducted by a panel consisting of a judge and a financial member, and their decision is binding on the Child Maintenance Service.
How long does the child maintenance challenge process take?: The entire process of challenging a Child Maintenance Service decision, including mandatory reconsideration and any subsequent tribunal appeal, typically takes between three and nine months. This timeframe applies to paying or receiving parents who disagree with a CMS calculation or variation decision and wish to pursue the formal challenge journey.
Who decides the appeal and is the decision final?: The tribunal hearing is conducted by a panel that includes a judge and a financial member. The decision made by this tribunal is binding on the Child Maintenance Service, meaning the CMS must follow the tribunal's ruling regarding the maintenance calculation or variation.