A trans person is suing the Internal Revenue Service in the US for not allowing her to write off her gender reassignment operation as a legitimate medical expense.

Trans activists are watching the case closely, as a defeat for the IRS would open the way for thousands of people to avoid paying tax on reassignment surgeries.

The IRS contend that such surgery is not “essential” and therefore cannot be claimed against.

Rhiannon O’Donnabhain, a 63-year-old former sailor, is due to have her case heard in Boston next week. She is originally from Ireland, and transitioned six years ago.

She claimed the expense of the operation on her 2001 tax return, but the IRS ruled two years later that it was not valid.

“This goes way beyond money. If I were to give the money back, it would be saying it’s OK for you to do this to me. It is not,” she told The Mirror.