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On the whole, recent changes in the law have meant that illegitimate children have much the some rights and responsibilities as legitimate ones. However, there are a few cases where it makes a difference, particularly in matters of succession.

A child is assmued prima facie to be legitimate if his or her parents are married to one another at the time of the child's birth. In most practical cases it is irrelevant whether the 'father' is the biological father or not; until recently it was not even possible to tell. To overturn the assumption of legitimacy it would be necessary to demonstrate that the legal father was not the biological father. If the parents divorce, or the father dies, between conception and birth the child is still legitimate. A child born legitimately is assumed under English law to have the same domicile as the father (see: Domicile). A legitimate child is in the joint custody of his or her mother and father, so long as they remain married.

An illegitimate child is one born to parents who are not married, or whose marriage is declared void (see: Void Marriage). The mother of an illegitimate child is under no obligation to disclose the identity of the father for the purposes of the birth certificate. An illegitimate child has the same domicile as the mother, and is assumed to be in the mother's sole custody. However, a court may make an 'affiliation order' against the father, obliging him to take a share of the custodial responsibility.

An illegitimate child may be 'legitimated', or declared legitimate, by the subsequent marriage of the child's parents, provided that the marriage is not void (as set out in Re Spence, deceased, Spence v Dennis and Another (1990)). In addition, a child who is adopted (see: Adoption) is deemed to be the legitimate child of the adopters.

If a child is legitimated, he or she has the same rights of inheritance as a legitimate child. However, this is now of limited importance as the annulls most of the difference between the inheritance rights of legitimate and illegitimate children.