It follows a five month absence from council meetings and duties by the 25-year-old.
Mr Tait, from Lockerbie, had attended just five meetings this year, with the most recent being the Lockerbie and Lochmaben Common Good Fund on April 12.
Since then he has missed meetings relating to social work, police, fire and rescue, full council, funding and others.
And, according to council policy, any member who fails to attend any meeting or function of the local authority in the space of six consecutive months will be ejected from their post.
However, before that could happen he quit – announcing his decision last night.
Lockerbie Academy educated Mr Tait won his seat in a by-election in November 2012 after the shock death of Ted Brown.
He was initially a member of the Conservatives but defected to Labour two years ago.
And it was rumoured he was about to resign from that party to become an Independent member.
Declining to explain his surprise decision further last night, Mr Tait would only say that he is meeting with the council directorate on Friday.
Reacting, fellow councillor Ian Carruthers said: “It’s absolutely shocking. At the end of the day, it was the Conservative vote that got him in and he turned his back on the party and went to Labour, and now he’s resigned and let all his constituents down.”
