The legal status of same-sex unions differs within the Bailiwick of Guernsey, a Crown dependency of the United Kingdom. Same-sex marriage became legal in the jurisdiction of Guernsey on 2 May 2017. Alderney recognises same-sex marriages performed abroad for some purposes and Sark does not recognise same-sex unions.
In Guernsey, civil partnerships performed in the United Kingdom and other relationships treated as such by UK law have been recognised for succession purposes in inheritance and other matters respecting interests in property since 2 April 2012, after approval of a bill allowing such recognition by the States of Guernsey on 29 June 2011. It received royal assent in the Privy Council on 16 November and was registered on the records of the island on 5 December 2011.
On 10 December 2015, the States approved an ordinance to recognise same-sex marriages and civil partnerships performed abroad for the purposes of the Income Tax (Guernsey) Law, 1975. It took effect on 1 January 2017. On the same day, the States directed the preparation of the legislation to amend the Inheritance (Guernsey) Law, 2011 to recognise abroad same-sex marriages for its purposes. The bill to this effect was submitted on 22 January 2016, and approved by the States on 2 March. It received royal assent in the Privy Council on 4 May and took effect upon registration on the records of the island on 16 May 2016.
On 17 June 2015, the States of Alderney unanimously approved the Inheritance (Alderney) Law, 2015, which include provisions to recognise same-sex marriages and civil partnerships performed abroad for its purposes. It received royal assent in the Privy Council on 8 October, was registered on the records of the island on 9 November 2015, and took effect on 1 January 2016.
In January 2014, it was announced that within the next twelve months deputies would debate whether to accept a state-recognised civil union proposal. The proposed law, titled Union Civile, was said to be "the most forward-looking marriage law" in the world. The measure would end state-sanctioned marriages of any couple and instead replace it with Union Civile. A consultation on the proposed Union Civile law began on 1 June 2015 and lasted until 13 July 2015. The proposed law would not apply to the entire bailiwick, but just to the islands of Guernsey, Herm, Jethou and Lihou. On 14 July 2015, the results of the consultation indicated that over 1,600 responses had been filed with the majority supporting the introduction of a same-sex marriage law rather than a partnership law.