回複：人在美國，若何繼承加拿大退休賬戶？

Normally I would not want to answer questions regarding foreign laws except intentional child custody or child support. In your case, however, you have some confusions regarding this retirement and as far as I know, canadian laws and us laws are similar in this point so I will try to answer. Double check with a canadian attorney for accuracy.

Regardless whether there is a will, a retirement plan such as a 401K, IRA, etc, is a will substitute. It is governed by contract law, which takes precedent to probate law. If the retirement plan named a beneficiary, then the beneficiary would take the benefit. If you know the plan named his mother as a beneficiary, then the spouse is irrelevant. There is nothing to determine, whether under us law or canadian law. From your next questions it is rather unclear who is a beneficiary. His father? His mother? Whether to roll over to an IRA or avoid reduction in SSI is of the beneficiary's concern, not yours.

If his father is the beneciary and he dies before taking the money, then the money will pass by his will, if he has one, or by intestate inheritance. The law where his father docimiled will govern.