A "front-end ratio" is the percentage of a person's monthly income allotted to mortgage payments and, usually, other housing-related expenses such as taxes and insurance. The front-end ratio is used in loan underwriting to help determine the amount of financing a person qualifies for. If you earned $100,000 per year and your lender said you could have a 30 percent front-end ratio, you could calculate your maximum allowable mortgage payments by dividing your annual income by 12 (100,000 / 12 = 8,333) and multiplying that figure by 0.3 (8,333 x 0.3 = 2,500), so you would be approved for monthly payments of no more than $2,500.