To meet their goals of early retirement, saving $500,000 is an appropriate amount, said Ed Rempel, a fee-for-service financial planner, tax accountant and blogger. To pay off the mortgage in the next five years, Kathy and Trevor will need to invest $6,300 a month in GICs — their desired strategy — and increase their mortgage payment by $2,200 a month to $4,600. The problem: they only have about $1,700 in monthly cash flow available now, said Rempel.