Local Government Code §111.041

(a) The commissioners court may spend county funds only in strict compliance with the budget, except as provided by this section. (b) The commissioners court may authorize an emergency expenditure as an amendment to the original budget only in a case of grave public necessity to meet an unusual and unforeseen condition that could not have been included in the original budget through the use of reasonably diligent thought and attention. If the court amends the original budget to meet an emergency, the court shall file a copy of its order amending the budget with the county clerk, and the clerk shall attach the copy to the original budget. (c) The commissioners court by order may amend the budget to transfer an amount budgeted for one item to another budgeted item without authorizing an emergency expenditure.