In response to a query on the methodology used to establish the kilometric rate for travel for medical expense tax credit purposes, CRA stated:
The CRA uses these kilometric rates according to guidelines from the Treasury Board of Canada Secretariat (TBS). These guidelines are based on the rates set by the National Joint Council (NJC) of the Public Service of Canada. The CRA has always accepted the NJC rates as fair and reasonable. The NJC determines the rates by analyzing new vehicle prices, depreciation and financing rates, current fuel prices, insurance premium rates, and operating costs in each province or territory. When these costs increase or decrease, the kilometric rates change accordingly.
…at njc-cnm.gc.ca/doc.php?did=117&lang=eng#tc-tm_4_1 … includes a link to the kilometric rates for each Canadian province and territory.