A loophole in the FIFA statutes, which has now been closed, allowed footballers who were British citizens, but born outside the UK, to play for any home nation, regardless of whether or not they have any previous connection to it. As none of the Channel Islands are affiliated to FIFA, and Tardif was born in Guernsey, he was therefore eligible to play for any home nation, and represented Northern Ireland at U19 level. He was called into the U21 squad in September 2001, for a European Championship qualifier against Malta, but did not play.
He spent the 2002–03 season on loan with Bournemouth, playing 14 games in all competitions and, after a spell on loan with Newport (Isle of Wight), in October 2003 joined Havant & Waterlooville on a month's loan, as cover for the injured Gareth Howells.
Released by Portsmouth, he joined Oxford United in May 2004, on a two-year contract. He was a regular the following season. However, he found first-team football hard to come by in later seasons, particularly under Jim Smith when Billy Turley kept him out of the side to the extent that he had a transfer request accepted by Oxford in December 2006. In September 2007, he retired from professional football to start a new career, although planned to continue playing semi-professionally.
Tardif played one game as a triallist for Eastleigh in October 2007, and joined Basingstoke Town in December 2007, moving to Maidenhead United in March 2008. He was an integral part of the Maidenhead side that narrowly avoided relegation at the end of the season, Tardif keeping four sheets in the final five games. He became a father shortly after the end of the season and chose to reduce the time spent travelling from his Portsmouth home by joining Farnborough in May 2008. He joined Bognor Regis Town in September 2008. He returned to Maidenhead United in the summer of 2009.
On 2 June 2010, Tardif rejoined Basingstoke Town. On 26 August 2010, Tardif had his Basingstoke Town contract terminated by mutual consent and returned to his home island, signing with St. Martins A.C.
Since returning to Guernsey, Tardif has represented Guernsey, in the 2011 Muratti Vase Final, losing on penalties to Jersey, at the 2011 Island Games and then won the 2012 Muratti Vase Final after Guernsey beat Jersey by two goals to nil Also, in 2011 Tardiff joined the newly formed Guernsey F.C. as their goalkeeper. In 2012, he played one match as a forward for Media United in the Guernsey FA Cup to ensure his eligibility for the Muratti.
