CDFI Bond Guarantee Program Improvement Act of 2023 This bill reauthorizes for four years and otherwise revises the Community Development Financial Institutions (CDFI) Bond Guarantee Program. Specifically, the bill (1) reduces the CDFI Bond Guarantee Program minimum issuance amount from $100 million to $25 million, (2) eliminates the cap on the annual number of guarantees, and (3) revises the amount to be held in a CDFI's relending account. (CDFIs are financial institutions serving low-income communities. Designation as a CDFI allows an institution to participate in programs such as the CDFI Bond Guarantee Program. The program provides financing to CDFIs through federal credit subsidies that allow CDFIs to issue bonds.)