You can formally change a name by filing documents with the court. These videos detail that court process, and include information specific to children and adults, and in connection with a divorce or marriage. One video addresses the objection process, for people who want to challenge a name change petition.
Note: Government agencies may have changed their policies since this video series was made. Contact those agencies or speak with a lawyer for up-to-date information. You can speak to a lawyer for free at the Maryland Court Help Center.
