Does an executor have to pay the deceased's unpaid debts out of his own money?

This isn't going to be a quick yes or no answer because, as with everything in law, much depends on the circumstances of each case. Here are some general rules you can work with.

The debts of an estate (including income tax) must be paid before any beneficiaries receive their money. If an executor ignores the debts and pays the beneficiaries, the executor may be held personally liable for those debts.

If paying the debts first means that the beneficiaries get little or nothing out of the estate, this is not the executor's fault.

Often an executor asks about debts because there are more debts than there are assets in an estate. An executor should a) honestly try to figure out what legally enforceable debts exist, b) be very careful to put appropriate values on estate assets, and c) use the estate assets to pay the debts. Where there is a lot of debt, this usually means selling assets to realize a cash value that can be divided among creditors. If there is not enough money to pay everyone 100% of what is owed to them, the executor may have to try to negotiate a settlement whereby each creditor gets a certain amount on the dollar.

If the estate is fully used up to pay the legally enforceable debts and expenses, and there are still debts of the deceased unpaid, the executor does not have to use his own money to pay them. That's assuming, of course, that the executor has not done anything fraudulent or negligent with the estate's money.

When listing the debts of an estate, the executor should remember to include debts that are not payable immediately but that will become payable in the future, such as income tax at the end of the year.

To protect himself or herself against personal liability, an executor should advertise in the newspaper for creditors and claimants against the estate. Doing so won't overcome any negligence on behalf of the executor, but assuming there is no negligence, advertising for creditors certainly helps.