The Department for Culture, Media and Sport (DCMS), who will be implementing the law, explained to Gay Star News why it will take so long.
They said their priority was to extend marriage to same-sex couples as soon as possible, mentioning the first weddings could take place earlier than summer 2014.
While the first same-sex marriages may be able to take place next summer, it will take longer for the law to allow civil partnerships to be converted.
‘Work is already underway and there is a lot to be done across government to ensure that all couples who want to get married; or convert their civil partnership to a marriage; or remain in their existing marriages when they change their legal gender, can do so,’ a spokeswoman said.
The changes the DCMS will be implementing include the court rules, IT systems, the processes for civil registrations, religious buildings registration, religious consents (when a marriage of a gay couple is conducted with religious rites but does not take place in a registered building - such as in a house-band, deathbed or a prison) as well as guidance for registrars, religious organizations and the public.
The spokeswoman added: ‘Parliament will also need to scrutinize a number of statutory instruments setting out how the new arrangements will apply to other legislation; on the detail of certain processes; and to ensure that marriages of same sex couples in England and Wales are treated in Scotland and Northern Ireland as civil partnerships.
‘This all takes time.’