What's used to calculate the housing debt-to-income ratio and total debt-to-income ratio?

After-tax income, or net income, is the amount remaining after all taxes have been deducted. While it reflects disposable income available for spending, it is not the figure used for calculating debt-to-income ratios, which require gross income to provide a clearer picture of a borrower's financial obligations relative to earnings.

Net income, similar to after-tax income, is the income remaining after all expenses and taxes. Although it indicates what a borrower can spend, it is not suitable for calculating debt-to-income ratios, as these calculations are based on gross income to ensure a standardized assessment of financial capacity before deductions.

Operating income refers to the earnings generated from a company's core business operations, excluding non-operational revenue. This term is primarily used in corporate finance. It does not apply to personal debt-to-income calculations, which rely instead on an individual's gross income to evaluate their debt service capability accurately.