Prevent mney mistakes today, and save big bucks tomorrow. Print Email PagesPrevious 4 of 18 Next View All 2. You pay your mortgage bill past the grace period HOW IT HURTS: It can knock 100 points off your credit score overnight, affecting your ability to get the best interest rates or a car loan. Related Links Save Money on Your Major BillsHow to Save More Cash (Now and in the Future!)Got bad credit? Bail yourself out.