The new law was registered in January but still requires approval from the States of Guernsey before it can come into force.
The debate is due to be held on 26 April, and if approved could come into effect on Tuesday 2 May.
Jersey has already approved same-sex marriage in principle and the necessary law changes could be in place by the end of this year.
Following the registration of the Guernsey law in January, two ordinances have been drafted, which are required in order to make necessary changes to other local legislation in preparation for its introduction.
The ordinances will be considered by the legislation review panel in early March.
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