Andover’s 15 municipal and school unions, represented by the Public Employee Committee for the purpose of negotiating health insurance changes, have rejected a rate proposal from Tufts Health Plan for the upcoming fiscal year that could have saved the town $486,000. The committee decided instead to stay with its current carrier, MIIA Blue Cross/Blue Shield, for fiscal 2015, which begins July 1. The two companies had submitted proposals in response to the town’s request for proposals for fiscal 2015. Although the process did not result in a change of carriers, the Board of Selectmen said “it allowed the town to leverage a much lower premium rate from MIIA.” In the end, the premium will rise 2 percent in the upcoming fiscal year, an increase of $349,019 over the fiscal 2014 premiums of $17.5 million. The town’s portion of the increase will be $269,025, with the remaining $79,994 assessed to the subscribers. Selectmen have instructed the town manager to start the request for proposals process earlier for fiscal 2016 to ensure greater transparency into the town’s efforts to control health insurance costs.