The deal represents a return for the 23-year-old son of former cross-code internationalist, Alan, who arrived on a month-long loan from Newcastle Falcons in September.
Born in Melrose, Tait came through Scotland's age-grade system with Edinburgh Rugby regulars Grant Gilchrist and Matt Scott, expressed his delight at this extended opportunity.
He said: "I'm really chuffed to get signed up."
"I couldn't believe it when I heard from Edinburgh Rugby. I loved my time at the club in September and wanted to stay but I was recalled by Newcastle."
"When I was there the new coaches had just arrived and basically told us that it was hard work that was going to get us through the season."
"From there it was all about playing hard, training hard and sticking to the systems."
"That suits me well. I like to get down and work hard and the club and the players are certainly doing that."
"This is a massive opportunity. I'm going to grab it with both hands and give it everything I've got."
Edinburgh Rugby head coach, Alan Solomons, added: "Michael [Tait] is a young player who we saw briefly earlier this season, and who probably didn't have enough time down at the club.
"What we did realise straight away is that he's a really good team man that fits into the Edinburgh Rugby environment very well."
"He's a bright young talent who comes out of the Borders region and this year-long contract will give him an opportunity to show what he can bring."
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland