The Upper Tribunal (Lands Chamber) recently made it clear that it was not up to the First Tier Tribunal (Property Chamber) to decide the proportions in which an unmarried couple shared the ownership of the family home.   In Hallman v Harkins [2019] UKUT 245 (LC) the Upper Tribunal concluded that "The FTT has no power to make declarations concerning the beneficial interests under a trust of land".  The FTT was therefore wrong to determine that Mr Hallman had a 65% interest and Ms Harkin had a 35% interest in the property.  

The Upper Tribunal made it clear that the courts are the proper forum for such decisions because the court can take into account issues involving children, the most appropriate financial remedy and the sale of the property. 

So, if you need a final decision as to how much of the family home each co-habitee owns you may need to apply to your local county court. But the proceedings will be expensive. You can expect each party to incur costs of at least £10,000. It is therefore the last option to consider if all other options fails. 

The first option is to get legal advice on your respective shares in the property. If you bought the property together you need to look at the TR1 form that you both signed during the purchase.  You may have set out in that form how you agreed to share ownership. 

If the relevant section of the TR1 form was not completed and there is no other written document setting out an agreement about ownership, it will depend on what you said or intended at the time you bought.   If the property is in only one person's name you will need legal advice on any evidence that shows an agreement to share ownership.

The best option, once you had good legal advice on your position, is to resolve the matter by negotiating an agreement.   The agreement might include a buy out by one party or the sale of the property.  It might involve a delay in the sale until the children reach a certain age.  Such a settlement can be taylor-made to the circumstances.   So long as the parties have good legal advice on the terms of the agreement, it is the best and most economic option for deciding the property interests of separating unmarried couples.