The top reason for billings on Motor Fuel Tax returns is reporting too much or not enough gallons in your ending inventory compared to what was reported as received and disbursed. Just check your numbers before you submit your report. If you started with 100 gallons in your beginning inventory, received no gallons and distributed no gallons, then you shouldn’t have an ending inventory of 75 gallons on your return. FDOR allows a small percentage in change from beginning to ending gallons due to heat and other natural/uncontrollable factors but not something huge like a 25% difference. So just check your figures when it comes to your beginning, received, disbursed, and ending inventory to eliminate a small mistake that can turn into a huge bill.