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Ontario has no law restricting puberty blockers, cross-sex hormones or surgeries for minors. Across Canada, Canadian Institute for Health Information data show double mastectomies on minors as young as 14. Ontario covers the cost through its public health plan.

National Post, 29 Sep 2023, reporting Canadian Institute for Health Information data

Anyone with an Ontario birth registration can apply to change the sex designation to M, F, or X. An adult application needs a sworn statement and a letter from a physician or psychologist. A driver's licence sex marker can be changed with an updated birth certificate.

ServiceOntario — change of sex designation on a birth registration

A male who identifies as a woman can be housed in a women's federal prison, even if his body is male and his identification still says male, unless a health or safety problem cannot be resolved. A federal count of 99 gender-diverse prisoners, from December 2017 to March 2020, found that 62 percent were males who identify as women. At the end of that count, 67 percent of that group were still in men's prisons. Ontario places a prisoner in the institution that matches the gender they identify with, or the housing they ask for, unless a health or safety problem cannot be resolved. A male who identifies as a woman can be held in a women's provincial jail. The federal women's prison in Ontario is Grand Valley Institution for Women in Kitchener.

Ontario inmate management policy; CSC Commissioner's Directive 100 (in effect 9 May 2022); CSC research report R-442