Like a divorce, an annulment ends a marriage. But unlike a divorce, when you get an annulment it’s as though you were never married, at least in some ways. Although you need to divide your property just like other divorcing couples, you are legally entitled to call yourself “single” after the annulment, rather than checking the box for “divorced” wherever that comes up.

Religion is the most common reason for choosing annulment over divorce. In particular, the Roman Catholic Church doesn’t sanction divorce or subsequent remarriage, but does allow someone whose first marriage was annulled to remarry in the church. But even if you get a religious annulment, in order to end your marital relationship in the eyes of the state you must obtain a civil annulment through the courts.

Although most annulments take place very soon after the wedding, some couples seek an annulment after they have been married for many years. In that case, the court considers all of the same issues as in a divorce, divides property, and makes decisions about support and custody. Children of a marriage that has been annulled are still legally considered “legitimate” children of the marriage.

In most places you can get a civil annulment for one of the following reasons:

Fraud or misrepresentation. One spouse lied about something that was important to the other in getting married, like the ability to have children.

No consummation of the marriage. One spouse is physically unable to have sexual intercourse, and the other spouse didn’t know it when they got married.

Incest, bigamy, or underage party. Either the spouses are related by blood so that their marriage is illegal under the laws of the state where they married, or one of them is married to someone else, or one of them is under the age of consent and didn’t receive a parent’s approval.

Unsound mind. One or both of the spouses was impaired by alcohol or drugs at the time of the wedding or didn’t have the mental capacity to understand what was happening.

Force. One of the parties was forced into getting married.

If you’re considering getting an annulment, you’ll need to talk to a lawyer. You can’t get an annulment just because you and your spouse agree that you want one—you have to prove one of the reasons listed above, and for that you will probably need a lawyer’s help.

Excerpted from Nolo's Essential Guide to Divorce, by Emily Doskow.