What if I have a sub-4% mortgage -- should I keep the house?

Keeping a mortgage rate far below today's market rate is a real financial advantage, but the decision to sell still depends on your equity, your next housing need and what that low payment is actually worth to your budget. Some owners rent the home out instead of selling, to hold onto the rate while still moving. Others sell anyway because a life change outweighs the payment savings. Run the numbers with your lender and agent rather than deciding on the rate alone.