Step-Parent C100 Application: How to Apply to Family Court

Step-Parent C100 Application: How to Apply to Family Court

A step-parent C100 application is the route many step-parents take when they want the family court to make a decision about a child they have helped raise. It usually comes up after a relationship ends, when the step-parent finds that the arrangements they had with a child simply stop. There is no automatic legal relationship between a step-parent and a stepchild, and that gap catches people out at the worst possible moment.

The good news is that the door is not closed. The C100 is the standard application form used for child arrangements, and the basics work the same way whoever is applying. What changes for a step-parent is whether you can apply straight away or whether you need to ask the court’s permission first. This guide covers both, the situations where an application makes sense, and what you will actually need to put on the form.

Can a Step-Parent Apply for a C100?

Yes. The C100 is used to apply for a section 8 order under the Children Act 1989, and step-parents are among the people who can use it. The three orders you can ask for are set out in section 8 of the Act:

• Child arrangements order: decides who a child lives with and who they spend time with. This is the order most step-parents are seeking.
• Prohibited steps order: stops someone taking a particular action, such as moving a child abroad or changing their school.
• Specific issue order: settles one disputed question about a child’s upbringing, such as medical treatment or schooling.

The distinction that matters is between people who are entitled to apply and people who need leave of the court, which is simply the legal term for permission. Section 10 of the Children Act 1989 sets out both groups. A step-parent can fall into either one depending on their circumstances, so it is worth working out which applies to you before you start filling anything in. If you want the wider picture on the different orders available, our guide to the types of child arrangements orders explains how each one works in practice.

When a Step-Parent Can Apply Without Permission

There are four routes that give a step-parent the right to apply without first asking the court. You only need one of them.

If you have parental responsibility

Parental responsibility is the bundle of legal rights and duties a person has towards a child. A step-parent does not get it by marriage alone. It comes either through a parental responsibility agreement signed by everyone who already holds it, or through a court order. If you have it, you are in the strongest position: you can apply for any section 8 order without permission, in the same way a parent can.

If you are or were married to the child’s parent

This route is often missed. If you were married to or in a civil partnership with the child’s parent, and the child was treated by you both as a child of your family, you are entitled to apply for a child arrangements order. Two details make this more generous than people expect. The marriage does not have to be subsisting, so a step-parent who has divorced the child’s parent still qualifies. And you do not need parental responsibility for this route to work.

If the child has lived with you for three years

This route does not depend on marriage at all, so it can help an unmarried partner who has been raising a child day to day. The three years do not have to be continuous, but the period must not have started more than five years before you apply, and it must not have ended more than three months before you apply. That last point matters. If a relationship broke down and you have been out of the home for four or five months, this route may already have closed, and you would be asking for permission instead.

When a Step-Parent C100 Application Needs Leave of the Court

If none of those four routes fits, you can still apply. You just have to ask the court for permission first, and the court decides that as a preliminary step before looking at the substance of your case. In practice you set out your grounds in the permission section of the C100 rather than filing anything separate.

A permission application is not a test of whether you will win. The court is deciding whether your application deserves a full hearing. Section 10 of the Children Act 1989 tells the judge to have particular regard to:

• The nature of the application: what you are actually asking for, and how reasonable it is.
• Your connection with the child: how long you were part of their life, what role you played, and how close the relationship is.
• Any risk of disruption: whether the application itself would unsettle the child’s life to the point of harming them.
• Local authority plans: where the child is in care, the authority’s plans and the parents’ wishes and feelings.

Step-parents often have a genuinely strong case on the second point. If you did school runs, bedtimes, homework and hospital appointments for years, say so clearly and concretely. Vague statements about caring deeply carry far less weight than a specific account of what you did and for how long.

When Might a Step-Parent Need to Apply?

Most step-parent applications come out of one of a handful of situations:

• The relationship with the parent has ended and contact with the stepchild has stopped or been heavily reduced.
• The parent you were with has died and the child’s other parent, or another relative, is now making all the decisions.
• The parent is unwell, in hospital or otherwise unable to care for the child, and you have been doing the day to day parenting without any legal footing.
• There is a specific decision in dispute, such as a school move or a proposed relocation, where a specific issue or prohibited steps order may fit better than a child arrangements order.
• You need to formalise arrangements that already work, so that schools, GPs and others recognise your role.

Where safeguarding is a live concern, there is a separate form to consider alongside the C100. Our guide to Form C100 and Form C1A explains when the C1A is needed and what it covers.

How to Complete a Step-Parent C100 Application, Step by Step

1. Attend a MIAM: a Mediation Information and Assessment Meeting is required before most applications about children, and that applies to step-parents in the same way it applies to parents. The mediator signs the MIAM section of your form. Some situations are exempt, and our guide to MIAM exemptions sets out when.
2. Work out your entitlement route: decide which of the four routes above applies, or accept that you will be asking for permission. Get this right before you write anything else, because it shapes the rest of the form.
3. State your relationship to each child: the form asks how you are related. Write “step-father” or “step-mother” rather than trying to describe yourself as a parent. Accuracy here helps you, it does not weaken your case.
4. Complete the permission section if it applies: set out your connection with the child, how long you cared for them, what you are asking the court to decide, and why it is in the child’s interests for the application to be heard.
5. Add a C1A if there are safeguarding concerns: this covers harm or risk of harm to you or the children.
6. Pay the court fee: the C100 fee is £270 as of July 2026, confirmed in the Ministry of Justice fee update. If money is tight, you may qualify for Help with Fees, which can reduce or remove it. Our breakdown of family court costs covers the wider picture.
7. Submit the application: most C100 applications are now filed online, and you can find the current version of the form on GOV.UK. Our step by step completion guide walks through the form page by page.

Does a Step-Parent C100 Application Give You Parental Responsibility?

Making the application does not, but the outcome can. If the court makes a child arrangements order naming you as a person the child lives with, and you are not a parent or guardian, you gain parental responsibility for as long as that order stays in force. That gives you a legal say in schooling, medical decisions and the other significant matters in a child’s life.

An order that says a child spends time with you does not carry parental responsibility in the same way. If parental responsibility is what you actually want, and the child’s parents are willing, a step-parent parental responsibility agreement can be a simpler and much less adversarial route than a court application.

Alternatives Worth Considering First

Court is not the only route, and for step-parents it is often not the best first move. Family mediation lets you and the child’s parent work out arrangements directly, which is usually quicker, less expensive and less stressful than a contested court process. It also tends to protect the working relationship you will need for years to come. Where the arrangement is intended to be permanent, a step-parent parental responsibility agreement, special guardianship or step-parent adoption may all be more suitable than a section 8 order, and each has its own process.

Frequently Asked Questions

About The Author

Jess Knauf

administrator

Jess Knauf is the Director of Client Strategy at Mediate UK, Co-founder of Family Law Service and lead author at C100form.co.uk.

With over six years of experience in family mediation across England and Wales, she specialises in C100 court applications, MIAM assessments, child arrangements guidance and divorce mediation. Jess is a member of Resolution, the national organisation of 6,500 family law professionals committed to constructive resolution, and the published author of “The Complete Guide to Divorce in England and Wales 2026” available on Amazon.

She fact-checks all family law content published across C100Form.co.uk to ensure accuracy and compliance with current UK legislation.

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