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An annulment declares that the marriage never existed. A divorce ends a valid marriage.
What if I don't get my marriage annulled?
That will depend upon whether the marriage is "void" or "voidable". Some marriages will be void even without an annulment; others require a person to get an annulment prior to the death of one person, or within a specific period of time (e.g. four years) or else the marriage will be considered valid.
What if the "spouse" dies in an invalid marriage?
What if you learn that your marriage was invalid only after your spouse dies? This will depend upon state law. If the marriage is considered void, it is likely that you will not be considered a "surviving spouse" under inheritance laws. If the marriage was only voidable, you probably will be considered a surviving spouse. But even if the marriage was void, you may have rights as a "putative" spouse that are similar to those you would have as a legal spouse.
Effect of delay on an invalid marriage
If you learn that your marriage was invalid, but don't do anything for a long time, can you still get an annulment? Perhaps, but many states would deny an annulment on various legal theories - for example, that by waiting so long you have "ratified" the marriage. Other states may have statues that require you to act within a specific period of time.
Effect of an annulled marriage on children
If a marriage is not valid, generally, an annulment has no legal effect on your children. Regardless of the annulment, the children will be considered legitimate and, of course, the parents will be responsible for their support.
Effect of annulment on alimony from prior spouse
Suppose your former spouse's obligation to pay me alimony ended when I remarried. If your second marriage is annulled, will your former spouse now have to start paying again?
Probably not, but it is possible in some states that the judge would revive the alimony obligation if the first marriage was void (as opposed to voidable).
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