How to Fill In the C100 Form in Wales

The C100 is the court form you use to apply for a Child Arrangements Order in Wales. It's the same form used across England and Wales, but the process that follows your filing is different in Wales because of the Pathfinder court model. Getting the C100 right matters — errors can delay your application or require resubmission, and the information you provide shapes the Cafcass Cymru investigation that begins immediately after filing.

Here's what each section requires and where parents most commonly go wrong.

Before You Start: What You Need Ready

Before opening the form, gather:

• Your FM1 mediator certificate — proof you attended a MIAM (Mediation Information and Assessment Meeting), or documentation of your MIAM exemption
• Full names, dates of birth, and addresses for both parents and all children
• Details of any existing court orders involving the children
• A C1A supplemental form if you're alleging domestic abuse or harm to the children
• The filing fee — £263 (rising to £270 from July 2026), or a completed EX160 fee remission form if you qualify

You can complete the C100 online through the MyHMCTS portal or submit a paper form. The bilingual Welsh/English version is available for paper submissions.

Section-by-Section Guide

Section 1: The children. List every child the application concerns. Include their full legal names, dates of birth, gender, and current living arrangements. Specify which parent they currently live with and their relationship to each applicant and respondent.

Section 2: The applicant(s). Your full details — name, address, date of birth, and contact information. If you have safety concerns about sharing your address, you can apply for it to be kept confidential from the respondent.

Section 3: The respondent(s). The other parent's details. If you genuinely don't know their current address, state this — but the court will need some way to serve the application.

Section 4: The orders you're applying for. This is the most important section. Be specific about what you want:

• A "lives with" order — naming which parent the child will live with primarily
• A "spends time with" order — setting out the schedule for the other parent
• A "prohibited steps" order — preventing the other parent from taking a specific action (like relocating with the child)
• A "specific issue" order — resolving a disagreement about a particular decision (like school choice)

State clearly what arrangement you're proposing. "I want the children to live with me" is weaker than "I am applying for the children to live with me during term time, spending alternate weekends and half the school holidays with the respondent."

Section 5: MIAM and mediation. Confirm that you attended a MIAM and attach the FM1 certificate. If you're claiming an exemption, identify which one and provide supporting evidence.

Section 6: Previous proceedings and existing orders. Disclose any previous court applications involving the children, including any orders currently in force. The court will check this, and omitting it damages your credibility.

Section 7: Other people and organisations. Name any other person who has parental responsibility for the children or who's involved in their care (grandparents living in the household, step-parents with PR, etc.).

Common Mistakes That Delay Applications

Not attaching the FM1 certificate. Without it, your application is returned unprocessed. If you're exempt from the MIAM requirement, you must explain which exemption applies and provide evidence.

Being vague about the orders requested. "I want to see my children more" isn't an order the court can make. Specify the schedule you're proposing — days, times, handover arrangements.

Forgetting the C1A. If there are any allegations of domestic abuse, substance misuse, or risk of harm to the children, you must complete the supplemental C1A form. Raising these issues for the first time at the hearing without having filed a C1A puts you on the back foot.

Using "custody" language. The form uses "lives with" and "spends time with." Writing "sole custody" or "full custody" signals unfamiliarity with the legal framework and can confuse the court's initial assessment.

What Happens After You File

In Wales, your C100 enters the Pathfinder system. A gatekeeping judge reviews the application and allocates the case. Cafcass Cymru begins their multi-agency investigation immediately — contacting police, children's services, schools, and health providers. Both parents receive safeguarding calls within the first few weeks.

The information you put on your C100 is what Cafcass Cymru reads first. A clear, child-focused application that explains your proposed arrangements and the reasons behind them gives the investigating officer a solid starting point.

The Wales Child Custody & Parenting Plan Guide includes a C100 filing checklist and section-by-section walkthrough designed for self-representing parents in the Welsh court system.

See more Wales guides →