Below market fixed rate. The rate on the SBA 504 portion is set when the SBA sells the debenture to fund the loan. Debenture sales occur monthly for 25-year loans, 20-year loans and bi-monthly for 10-year loans. The rate is then fixed for the term of the loan. SBA 504 Debentures are government guaranteed securities. The effective rate (APR) will include program fees and a loan loss subsidy.