Public single-sex spaces across England, Scotland and Wales are now officially organised by sex assigned at birth, following new guidance that came into effect yesterday.

The guidance, issued by the Equality and Human Rights Commission, says transgender people should use either gender-neutral facilities or those matching their sex assigned at birth, rather than their gender identity.

The code is not legally binding, but it strongly encourages businesses and service providers to follow the guidance when providing single-sex services under the Equality Act.

The changes have been strongly criticised by transgender rights groups and some politicians. The Scottish Greens described the guidance as “authoritarian and cruel”, warning it could make daily life less safe for trans people and lead to intrusive questioning of anyone who does not fit traditional gender stereotypes.

The Good Law Project also condemned the guidance, saying it could exclude and segregate transgender people. The organisation argues that encouraging separate facilities risks stigmatising trans people and could force them to reveal their transgender status in everyday situations.

The guidance follows a UK Supreme Court ruling earlier this year on the definition of sex in the Equality Act, which prompted the EHRC to update its advice for organisations providing single-sex spaces and services. While the code itself does not create new law, it is expected to influence how businesses, public bodies and other organisations interpret their legal responsibilities.

Supporters of the guidance say it provides greater clarity for organisations offering single-sex services. Critics, however, warn it could have a significant impact on how transgender people access public spaces across Britain.