Legal requirements for marriage
By law, two consenting individuals are allowed to marry if both are at least 18 years old. Under the age of 18, the couple needs a statement of consent issued by the parents. In Germany, civil marriage is built on the premise of monogamy and can therefore only be performed if neither party is already married to someone else. As of October 2017, same-sex couples can also get married in Germany. Before, these couples had the possibility to enter a civil union (Eingetragene Lebenspartnerschaft). This type of union cannot be entered any longer, though existing civil unions remain valid.
The registry office (website in German) in your district can provide you with further information based on your specific situation. It's advisable to start the preparations for your marriage at least six months in advance. Depending on your country of origin, you may need to gather translations of official documents such as birth certificates or proof of termination of any previous marriages. Also, make sure that your marriage in Germany is legally recognised in your home country. To clarify all matters, contact your embassy or consulate.