Everyone in the Channel Islands must contribute to the upkeep of churches by paying Parish Rates, however, Leo Thomas has said this year he will give the £7.94 he paid in 2016 to a local charity instead.
In an open letter seen by BBC Guernsey, he wrote: "As a person classed as a sinner and not worthy to get married in a church why should I be obliged and forced to pay a penny towards the costs of said church?
"If the Church of England was a private company, I probably would have a strong case of discrimination in court."
Anglican Dean of Guernsey, Very Rev Tim Barker, refused to comment but said he would respond to Mr Thomas privately, BBC Guernsey said.
Legislation approving same-sex marriage was approved in Guernsey last December, however, it isn't expected to come into effect until this summer.
States of Guernsey Deputy Peter Ferbrache said while he sympathises with Mr Thomas withholding rates contributions is wrong.
According to the BBC, he said: "I regard the church buildings as an important part of our heritage. They should be preserved."