Have you ever wondered how credit works? And what happens if you don’t pay your bills on time. The Fair Isaac, which developed FICO scores, uses a comparison between two people to explain how mortgage delinquencies affect credit scores.

Fair Isaac derived these numbers from a theoretical calculation based on hypothetical borrowers – one with an initial score of 675 and one with an initial score of 775. FICO scores range from 300 to 850.

The hypothetical person behind the 675 score had six credit accounts, while the person with the 775 score had 10. The consumer with the 775 score had no missed payments other than the mortgage; the 675 example had two late payments before they failed to pay the mortgage.

After a mortgage delinquency, the two scores would look like this:

• After 30-day delinquency, 675 score drops to 620 to 640; 775 score declines to 670 to 690.

• After 90-day delinquency, 675 score falls to 595 to 610; 775 score goes to 645 to 665.

• After short sale, foreclosure, or deed-in-lieu, 675 goes to 575 to 595 and 775 drops to 620 to 640.

• After bankruptcy, 675 drops to 530 to 550; 775 declines to 540 to 560.