The Civil Partnership Act came into force in December 2005. In their most recent bulletin on civil partnerships, the Office of National Statistics found that there were 956 partnerships formed in England and Wales in 2018. This has increased 5.3% compared with 2017. This marks the third annual increase since the larger decrease between 2013 and 2015 after the introduction of the Marriage (Same Sex Couples) Act 2014.
Article 12 protects the right of men and women of marriageable age to marry and start a family. The European Court of Human Rights ruled in 2002 that this right extends to transgender people who are now able to marry or enter civil partnerships in their acquired gender because of the Civil Partnership Act 2004 means that gay men and lesbian women in the UK are now able to register civil partnerships. Couples who register a civil partnership have the same rights as heterosexual married couples in areas like tax, social security, inheritance and workplace benefits. Following the enactment of the Marriage (Same Sex Couples) Act, same sex couples can now marry in civil ceremonies, or religious ones where the religious organisation allows it, throughout England and Wales. Same sex marriages have been legalised Scotland in 2014 and in Northern Ireland in 2020. Additionally, married transgender men and women are now able to change their legal gender without having to end their marriage in England, Scotland and Wales.
Civil partners who wish to convert their civil partnership into a marriage are also able to do so in England, Scotland and Wales.
The Equality Act protects those who are married or in a civil partnership against certain types of discrimination. 
This is when someone is treated differently or not as well as others because they are married or in a civil partnership. For example, a promotion is not given to a married member of the team because they need to be willing to travel, and the employer feels the job would be better suited to a single person.
Note that in relation to marriage and civil partnership, direct discrimination by perception or association does not apply.
This occurs when a rule, practice or procedure is applied to all workers, but disadvantages people who are in a civil partnership or marriage. Indirect discrimination can only be justified if the practice is necessary for the way the business works, the employer can show they have looked at less discriminatory alternatives, and there is no other way of achieving it.
This occurs when an individual is treated badly the recipient has complained, or supported someone who has made a complaint, under the Equality Act.
Circumstances when being treated differently due to marriage or civil partnership is lawful
In some circumstances an employer can refuse to employ you because you are married or in a civil partnership if the work is for the purposes of an organised religion. This example may be relevant when recruiting a Catholic Priest. Harassment is not applicable in relation to marriage and civil partnership.
Information and Support
Acas Report on Marriage and Civil Partnership Discrimination
Equality Advisory & Support Service