Jan. 9/14-Jazz 8588, a de Havilland DHC-8-402 (C-GGNF) landed on runway 27 at Saskatoon, SK, on a flight from Calgary, AB. The aircraft touched down about 1000 feet down the runway, and slowed to taxi speed. The crew planned to exit onto taxiway “A” at the end of the runway. On reaching the turnoff, the aircraft did not respond to steering or braking inputs and departed the end of the runway at about 20 kts. The aircraft came to rest 50 feet past the end of the runway in about 1.5 feet of snow. There were no injuries and there was no damage to the airport facilities. The crew advised ATC, completed shutdown checks and briefed the passengers. ARFF responded and TSB was notified. Airport crews cleared snow from around the aircraft and the passengers were taken by bus to the terminal. The aircraft was towed to the ramp for inspection and no damage was found. ATIS information indicated a CRFI of .52 for runway 27 at the time of the aircraft’s initial approach. An area of ice with poor braking action was noted at the end of runway 27 in the vicinity of the turnoff onto taxiway “A”.