Headline Politics Finance Minister Jim Flaherty announces new rules for government-backed mortgages in Ottawa. The maximum amortization period for large mortgages is being reduced from 35 years to 30 years. The maximum borrowing amount for refinancing is also being cut from 90 per cent to 85 per cent.  Government insurance backing is also being withdrawn for lines of credit secured by homes. The first two rules take effect on March 18, the latter one month later.