How to Fill In C100 Form 2026: Step-by-Step Guide | UK
Need to fill in C100 form for child arrangements? This step-by-step guide shows you exactly how to fill in C100 form correctly in 2026, avoid common mistakes, and give yourself the best chance of success. At McKenzie Friend London, we help parents fill in C100 form applications every day.If you’re a parent who can’t agree on arrangements for your children and you need the family court to help, you’ll need to complete a C100 form. This 28-page document is the gateway to child arrangements proceedings in England and Wales, and getting it right the first time can save you weeks of delays and potential rejection.
At McKenzie Friend London, we help parents navigate this process every day. This guide explains exactly how to fill in your C100 application, avoid common mistakes, and understand what the court needs from you.
What Is a C100 Form and Why Do You Need to Fill In C100 Form?
A C100 form is the official application used to ask the family court to make decisions about children under Section 8 of the Children Act 1989. You might need one if you want to apply for:
- Child Arrangements Order – to decide where your child lives and how much time they spend with each parent
- Specific Issue Order – to resolve a particular disagreement (e.g., which school your child attends)
- Prohibited Steps Order – to prevent the other parent from taking certain actions (e.g., moving abroad with your child)
The current court fee is £263, though you may qualify for help with fees if you’re on a low income or certain benefits.
Before You Start: The MIAM Requirement
Since 2014, you must attend a Mediation Information and Assessment Meeting (MIAM) before submitting a C100 form. This is a legal requirement, and the court will not accept your application without proof that you’ve attended one or that you qualify for an exemption.
At your MIAM, an accredited family mediator will discuss your situation and explain whether mediation might help you reach an agreement without going to court. If mediation isn’t suitable, the mediator will sign page 12 of your C100 form, confirming you’ve attended.
Important: Your signed MIAM certificate is only valid for 4 months, so don’t delay submitting your application once you have it.
MIAM Exemptions
You may be exempt from attending a MIAM if:
- There is evidence of domestic abuse
- Your application is urgent (e.g., risk of child abduction)
- The other party is in prison or subject to bail conditions
- You or the child are at risk of harm
- There are child protection concerns involving social services
How to Fill In C100 Form: Step-by-Step
Tip: Print the form and complete it in pencil first. This allows you to make corrections before submitting your final version.
Section 1: Your Details (The Applicant)
Enter your full name, date of birth, and address. If you have concerns about your safety and don’t want the other parent to know your address, you should also complete a C8 Confidential Address Form and submit it alongside your C100.
Section 2: The Other Parent (The Respondent)
Provide as much information as you can about the other parent, including their full name, date of birth, and current address. If you don’t have all these details, include what you know and explain any gaps.
Section 3: The Children
List all children included in your application, starting with the oldest. Include their full names, dates of birth, and your relationship to each child. You’ll also need to confirm whether each child is known to social services.
Section 9: What You’re Asking For (The Most Important Section)
This is where you explain what order you want the court to make and why. Be specific and child-focused. For example:
“I am applying for a Child Arrangements Order so that [child’s name] lives with me and spends time with their father every other weekend from Friday after school until Sunday at 6pm, plus half of school holidays. This arrangement would provide stability for [child’s name] while maintaining a meaningful relationship with their father.”
Avoid emotional language or accusations. Focus on what’s best for your children and provide practical proposals.
Common Mistakes When You Fill In C100 Form
- Missing MIAM certificate: The court will reject your application without it
- Incomplete respondent details: Provide as much as you know; leave gaps blank rather than guessing
- Vague or emotional Section 9: Be specific about what you want and why it benefits the children
- Not attaching C1A form: If there’s any history of domestic abuse or harm, you must include this
- Forgetting the fee: Include payment or your Help with Fees reference number
What Happens After You Submit?
Once your C100 is accepted, the court will issue your application and send a copy to the other parent. CAFCASS (Children and Family Court Advisory and Support Service) will conduct safeguarding checks and contact both parents by phone before your first hearing.
Your first hearing, called a First Hearing Dispute Resolution Appointment (FHDRA), is typically listed within 4-6 weeks of your application being issued. However, with current court delays averaging 47 weeks for private law cases, be prepared for a longer process to final resolution.
Need Help with Your C100 Application?
At McKenzie Friend London, we specialise in helping parents complete their C100 applications correctly the first time. We can review your form, help you write Section 9, and ensure you’ve included everything the court needs.
Book a free initial consultation today and let’s discuss your situation. Call us on 07958 361 168 or email alex@mckenziefriendlondon.co.uk.
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📄 Get the Complete C100 Application Guide — £19.99
This blog covers the basics. The full guide goes section by section through every part of the C100, with two worked examples for Section 9, a complete MIAM Exemption Checklist with every exemption and the evidence you need, a C1A Companion Guide for drafting specific allegations, and a 40-item application checklist so nothing gets missed.
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👉 Download the C100 Application Guide: mckenziefriendlondon.co.uk/resources
Once your C100 is filed, your FHDRA will be listed within 4–6 weeks. Our FHDRA Preparation Pack (£39.99) gives you everything you need for that first hearing — including a position statement template, Cafcass safeguarding letter guide, and a list of orders you can ask for.