After-Tax Interest Expense

Category

Ratios

Units

Currency

Formula

After-Tax Interest Expense = Interest Expense × (1 − Effective Tax Rate)

Source

Calculated by GeminIQ from figures reported in SEC filings

After-tax interest expense is a company's interest expense reduced by the income tax savings that the interest deduction produces, calculated as interest expense multiplied by one minus the effective tax rate. It shows the true cost of borrowing to the company once the tax benefit of deducting interest is taken into account.

Because interest is generally deductible, every dollar of interest lowers taxable income and therefore lowers the tax bill. After-tax interest expense strips that saving out, leaving the net burden that debt places on earnings. It is not a line item companies report. It is calculated from figures reported in SEC filings.

The two inputs come from the income statement. Interest expense, usually tagged InterestExpense in XBRL, is the cost of borrowed funds that a company recognized as an expense in the period, the amount Regulation S-X Rule 5-03.8 calls interest and amortization of debt discount and expense. The tax rate is typically the effective rate, found by dividing income tax expense (IncomeTaxExpenseBenefit) by pretax income. Some analysts use the statutory rate instead, which for US corporations has been 21% at the federal level since the 2017 tax law change.

The choice of rate matters. A company with large tax credits, foreign earnings taxed at lower rates, or operating losses can show an effective rate far from the statutory rate, and in a loss year the calculated rate may be negative or meaningless. Many analysts cap the rate between 0% and 100% for that reason. Interest that a company capitalizes into the cost of an asset under construction is not in reported interest expense, so the figure reflects only interest that passed through the income statement.

The measure is mainly a building block. Adding after-tax interest back to net income or operating cash flow removes the effect of how a company is financed, which is how analysts arrive at free cash flow to the firm and at returns on total capital. It is also the numerator of an after-tax cost of debt when divided by average borrowings.