A post specifically for the trans guys. I wanted to just share that medicare seems to be quite flexible with gender markers and gap item numbers. I have changed my gender marker to male in their system, and the recent surgery I had was processed through with female item numbers (due to the issue I had with medibank private changing their policy inclusions).
In conclusion I've personally experienced that it is possible to change your gender officially with male with medicare (to get less expensive testosterone) and still put the female surgery item numbers through with them. You are just required to send the forms into their head office (as a counter assistant can't process it) and it takes about 10 days to get the medicare rebates; they then send the claim form onto a private health fund you may belong to for additional claim rebates in the same way (i.e. processing female surgery items under a male gender profile). However if you approach your private health fund directly their system can deny it, it has go through the 'medicare first claim system'.