Mississippi Code Title 21. Municipalities § 21-35-23

All appropriations, other than appropriations for uncompleted improvements in progress of construction, shall lapse at the end of the fiscal year. The appropriation accounts shall remain open for a period of thirty days thereafter for the payment of claims incurred against such appropriations prior to the close of the fiscal year and remaining unpaid. After such period shall have expired, all appropriations, except as hereinbefore provided regarding uncompleted improvements, shall become null and void, and any lawful claim presented thereafter against any such appropriation shall be provided for in the current budget.