How do you find the cost of debt when building a financial model?

If it’s a public company, you can look up the cost of debt on Bloomberg
or in their company filings. Different types of debt are often listed in the
notes to the financial statements in a quarterly or annual report and the
interest rate is sometimes provided.

If it’s a private company, you can create “debt comps” by finding public
companies that are comparable and finding their median cost of debt.

Finally, you can try to calculate the cost of debt as a key benchmark
plus a spread, such as LIBOR + 500 bps (500 bps = 5%). The spread will
depend on the credit risk of the company, determined by the stability of
their cash flows as well as many qualitative factors.