It depends on the status of your relationship.
Firstly, if the down payment was given to you by your parents to fund the acquisition of a home that eventually became your matrimonial home, i.e. the home in which you lived throughout your marriage and at the time of the separation, then you cannot get the money back.
With matrimonial homes the couple must share the full value of the property regardless of who paid for it or owns it. Pursuant to the s. 4(1) definition of net family property and paragraph 1 in the s. 4(2) exclusions a matrimonial home is never excluded from the calculations leading to an equalization payment.
If instead you and your partner are common law and not legally married then you may make a claim for a resulting trust so that the value of your parents’ contribution can be returned to you.
A resulting trust contemplates that one party financially contributes to the acquisition of a piece of property, in whole or in part, and as a result becomes the beneficial owner of the property. The other party (or parties), instead, is given legal title to the property and hold it in trust for the beneficial owner. Moreover, there was a common intention that a resulting trust would arise based on the different contributions made. Then, upon separation the beneficial owner is entitled to an interest or share in the value of the property proportionate to his or her contribution.
Therefore, if your parents contributed financially and legal title was put in your name or your spouse’s name or is held jointly by you and your spouse then your parents may be deemed part beneficial owners of the property and can get their money back.
The same reasoning applies to a claim for a constructive trust except there is no need for a common intention to be found and the parties must satisfy the principles of unjust enrichment and show that there is a connection between the contribution made and the property in question.
Lastly, you can make a simple claim for unjust enrichment. This will require that you show that based on your parent’s contribution (a deprivation) your spouse was unjustly enriched and there was no legal reason for the enrichment and so they should be compensated.