Fannie Mae plans to increase its allowable debt-to-income ratio from 45% to 50% on July 29. This means that more borrowers on the cusp of getting a loan (e.g., millennial, first-time, and lower- to moderate-income borrowers carrying more debt) could potentially qualify for a mortgage backed by Fannie.

The debt-to-income ratio is calculated by taking a potential borrower's monthly gross income and dividing it by the borrower's recurring debts such as monthly car payments. Lenders use this ratio to figure out if borrowers can afford to make their mortgage payments each month.