Cost of Debt
Name variants
- English
- Cost of Debt
- Katakana
- コスト
- Kanji
- 負債
Quality / Updated / COI
- Quality
- Reviewed
- Updated
- Source
- Citations & Trust
- COI
- none
TL;DR
Cost of debt helps choose financing mix by clarifying borrowing costs and the trade-offs between cost and flexibility. It keeps scope and assumptions aligned.
Definition
Cost of debt is the effective interest rate a company pays on its borrowings, often adjusted for taxes. It specifies the unit of analysis and the assumptions behind borrowing costs, including tax rates and covenant terms. The concept separates what is in scope (interest expenses, fees, and credit spreads) from what is out of scope (equity costs), so comparisons stay consistent. Applied well, it turns a vague debate into a measurable choice and makes the drivers of results explicit.
Decision impact
- Use Cost of Debt to decide financing mix and project hurdles, because it exposes borrowing costs and the trade-off with cost versus flexibility.
- It changes budgeting and prioritization by making tax rates and covenant terms explicit and reviewable.
- It informs adjustments when credit ratings or rate environments change, so the decision stays grounded in current conditions.
Key takeaways
- Define the unit and time horizon before comparing borrowing costs across options.
- Track the primary driver (after-tax borrowing rate) separately from secondary noise.
- Run sensitivity checks on refinancing terms and leverage to avoid false precision.
- Document data sources and calculation steps so results are auditable.
- Revisit the metric when the business model or market context changes.
Misconceptions
- Cost of debt is not just the coupon rate; fees and discounts matter.
- Low cost of debt does not imply low overall risk.
- Ignoring tax effects can misstate true borrowing costs.
Worked example
A CFO evaluates issuing fixed versus floating-rate debt. The CFO models after-tax borrowing cost under different rate paths and covenant constraints. The analysis favors fixed-rate debt given expected rate hikes. After issuance, the firm monitors credit spreads and refinancing options.
Citations & Trust
- Principles of Finance (OpenStax)