UK How annulment differs from divorce
A divorce ends a marriage that was validly formed. Annulment — also called nullity — deals with a marriage that was never validly formed at all (a 'void' marriage), or that was valid but can be treated as ended because something was wrong from the start (a 'voidable' marriage).
There are two practical differences that matter. First, you can apply for an annulment during the first year of the marriage, whereas a divorce cannot normally be started until you have been married for at least a year. Second, if the marriage is void the law says it never existed — which is not the outcome of any divorce.
GOV.UK puts it plainly: you can apply for annulment in the first year or any time after, but if you apply years after the wedding you may be asked to explain the delay.
A void marriage: never legally valid
The grounds on which a marriage is void are set out in section 11 of the Matrimonial Causes Act 1973. In broad terms, a marriage is void if the parties are within the prohibited degrees of relationship; if either party was under 18 (or under 16 for a marriage before 27 February 2023); if either party was already lawfully married; or in certain cases involving a polygamous marriage entered into abroad.
Because a void marriage was never valid, the law treats it as never having existed. That does not mean you can simply ignore it: you may still need the court's paperwork — a decree of nullity, sometimes called a nullity of marriage order — to prove the position, for example if you want to marry again or to sort out money and property.
A voidable marriage: valid unless and until it is annulled
A marriage is voidable on the narrower grounds in section 12 of the 1973 Act. These include that the marriage was never consummated, either because one party was incapable of consummating it or because the other wilfully refused (this ground does not apply to same-sex couples); that a party did not properly consent to the marriage; that at the time of the marriage the respondent had a sexually transmitted disease, or was pregnant by someone else; or that one spouse was in the process of transitioning to a different gender.
The distinction from a void marriage is important. A voidable marriage exists until it is annulled, so it can carry the same financial consequences as a divorce, and the court applies the same discretionary powers over money and property. There are also time limits and other bars in section 13 — several of the grounds must be relied on within three years of the marriage, and for some the applicant must not have known the relevant facts at the time. Whether a bar applies to your case is exactly the kind of question to put to a solicitor.
Annulment is not a way to avoid the money questions
Some people are attracted to annulment because they believe it wipes the slate clean. It does not. The court's powers to redistribute money, property and pensions apply to nullity proceedings as they do to a divorce, and a decree of nullity for a voidable marriage only annuls the marriage from the date it is made — the marriage is treated as having existed up to that point (section 16 of the 1973 Act).
If there are children or assets, the financial issues are substantially the same as on divorce, and the court will look at the same statutory factors. A solicitor will tell you whether annulment or divorce is the correct route on your facts; producing the wrong kind of application only costs time and money.
Scotland and Northern Ireland
The UK is three legal systems, and 'annulment' is not a single thing. In Scotland the route is a declarator of nullity of marriage rather than a divorce, and the grounds and terminology differ from England and Wales. A marriage can be void where consent was given only by reason of duress or error (see the Marriage (Scotland) Act 1977 as amended by the Family Law (Scotland) Act 2006), and financial provision on a declarator follows the Family Law (Scotland) Act 1985. In Northern Ireland nullity is also available under its own procedure and its own courts. If you are unsure which applies to you, take advice regulated in the right jurisdiction before doing anything.
When annulment is not the answer
Most people who ask about annulment actually want a divorce. If the marriage was validly entered into and none of the grounds applies, annulment is simply not available, and the correct route is a divorce — or, in the first year of marriage, a judicial separation or a separation agreement while you wait.
Be cautious of anyone advertising a quick or guaranteed annulment. Whether a marriage is void or voidable, and whether a ground is made out, is decided by a court, and the grounds are narrow on purpose.
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