Gender Self-Identification ruled out
in England
The process today (which 95% of applicants use):
A declaration that they will live permanently in their acquired gender
A medical report of a gender dysphoria diagnosis
A medical report of any hormone treatment or surgery, or any planned treatments
Evidence they have lived full time in their acquired gender for at least two years, such as copies of their passport and driving license
Applicants also must be 18 or over and pay a fee
https://www.bbc.com/news/explainers-53154286
Some trans rights activists had called for self-identification which would have meant that someone who declared themselves to be a different gender, were, under law. It was unclear what, if any, process would be endorsed. Some trans-adults suggested that the current process was intrusive and took too long.
There was backing for so-called self-id from Stonewall, UK and others.
Some groups did not back this arguing that sex based rights were threatened if there was simple 'self-id.' Fair Play for Women argued this threatened sports, since self-identification could mean biological men who had no formal diagnosis or treatment could then participate in female sports if they self-identified as women.
Ministers will, however, reduce the standard fee for changing one's gender.
https://www.bbc.com/news/uk-politics-54246686