Yes, a debt unknown at the time of accepting the inheritance may have to be paid. However, its discovery does not automatically make the heir personally liable beyond the value of the assets they inherit.
The fact that a debt of the deceased is discovered after the inheritance has been accepted does not extinguish that debt. If it is valid and legally due, it must be taken into account in the settlement of the estate, in accordance with the applicable rules.
In principle, heirs are not liable for the debts of the deceased beyond the value of the assets they receive, provided that the rules of the Civil Code of Quebec relating to the inventory of the estate and the liquidation of the estate have been respected, subject to the exceptions provided by law.
If the debt is discovered during the liquidation, the liquidator must in particular verify its validity and amount, then determine its consequences on the solvency of the estate before continuing payments or proceeding with the distribution of assets to the heirs.
If the debt remains unpaid after the estate is settled, specific rules apply. When there is only one heir, that heir is generally liable for the outstanding debts up to the value of the assets they inherit. When there are several heirs, each is generally liable in proportion to their share of the estate, subject in particular to the rules applicable to indivisible debts.
Special rules also apply when the will provides for a bequest of universal usufruct, particularly with regard to the legatee's liability to creditors and the distribution of debts between the usufructuary and the bare owner.
When a debt is discovered after regular payments have been made, the Civil Code of Québec also provides specific conditions for the recourse of creditors who have remained unknown. These recourses may depend, in particular, on the reasons why the creditor was unable to come forward in a timely manner and the time elapsed since the liquidator's discharge.
The situation may differ, however, when an heir has waived an inventory, has commingled the estate's assets with their personal property, or has failed to comply with certain legal obligations. In these circumstances, they may be liable for debts exceeding the value of the inherited assets.
When an heir is in good faith and the discovery of a previously unknown debt substantially alters the extent of their obligation, the Civil Code of Quebec provides, under certain conditions, for the possibility of asking the court to reduce this obligation or to limit their liability.
The discovery of an unknown debt must therefore be analyzed according to the time it is discovered, the state of the liquidation, compliance with the rules relating to the inventory, the assets already distributed and the extent of the responsibility of each heir.