Fannie Mae Connecticut Avenue Securities Trust 2023-R04 (CAS 2023-R04) is structured as a real estate mortgage investment conduit (REMIC), which could help protect investors from counterparty risk exposure to Fannie Mae. The notes are issued from a trust with assets that primarily consist of the note proceeds (held in the cash collateral account [CCA]), investments on those proceeds, and the designated Q-REMIC interests. The transaction has a 20-year final maturity in May 2043, with an early redemption option in May 2028 or when the aggregate unpaid balance of the reference obligations is less than or equal to 10.00% of the cutoff date balance.