Adherence to the dress code set for other female employees would be appropriate. Likewise a person whose sex at birth was female, who also identifies as female, would be expected to adhere to the female dress code. If the same individual identifies as male, the male dress code would apply. If a person generally and with reasonably consistency relates to others as a member of the gender to which they desire admission, they should be regarded as such and held to the same standards. Transsexual, and transgendered persons who are dealing with gender identity issues, dress consistently in clothing appropriate to their identity.
Documentation can substantiate an individual's claim to being transsexual or transgendered.
Under current practice, an employer has a right to ask for documented substantiation of claim that a person is dressing in the clothes usually associated with the other gender as part of a gender identity treatment process. Employers retain the right to set usual workplace standards of dress.