Every truck on a Form 2290 is taxed by its weight category, and the category comes from one figure: taxable gross weight. Get that number wrong and the whole return is wrong — too low and you owe more later, too high and you have overpaid.
The IRS lists it as one of three things to have ready before you start, alongside your EIN and each VIN.
The three parts of taxable gross weight
For any vehicle other than a bus, taxable gross weight is the total of:
- The actual unloaded weight of the vehicle, fully equipped for service.
- The actual unloaded weight of any trailers or semitrailers, fully equipped for service, customarily used in combination with the vehicle.
- The weight of the maximum load customarily carried on the vehicle and on those trailers or semitrailers.
A trailer counts as customarily used with a vehicle if the vehicle is equipped to tow it. So a tractor set up to pull a 53-foot trailer is weighed with that trailer, even on days it runs bobtail.
What fully equipped for service includes
Actual unloaded weight means the empty (tare) weight of the vehicle fully equipped for service. The IRS spells out what that covers:
- The body, whether or not it is designed to carry cargo — a concrete mixer counts.
- All accessories, and all equipment attached to or carried on the vehicle for its operation or maintenance.
- A full supply of fuel, oil, and water.
And what it leaves out: the driver; any equipment (other than the body) mounted on or attached to the vehicle to handle, protect, or preserve cargo; and special equipment such as an air compressor, crane, or specialized oilfield equipment.
Buses are figured differently: actual unloaded weight fully equipped for service plus 150 pounds for each seat for passengers and the driver. See Form 2290 for buses.
Choose the category your weight falls in and the month the truck was first used — the calculator does the rest.
Your state registration sets the floor
The IRS warns that the weight you declare to register the truck in a state can control the taxable gross weight. Which rule applies depends on how your state registers vehicles:
| How the state registers the vehicle | What that means for Form 2290 |
|---|---|
| By a specific declared gross weight (including prorated or proportional registration) | Taxable gross weight can't be less than the highest gross weight declared in any state. For a tractor-trailer or truck-trailer combination, no less than the highest combined gross weight declared. |
| By gross weight category, and not in any state that requires a specific declared weight | Taxable gross weight must fall within the highest gross weight category the vehicle is registered for in that state. |
| Only on actual unloaded weight | Taxable gross weight is the total of the three parts above. |
In practice: if your IRP cab card or state registration declares 80,000 lb, that is your floor, even if the truck rarely scales that heavy.
Special permits don't count — with one limit
Weights declared only to get special temporary travel permits are left out. Those are permits that let a vehicle run in a state where it isn't registered, above a state's maximum weight limit, or above the weight it is registered at in that state.
The exception: permits issued for your vehicle that together cover more than 60 days — or, if issued monthly, more than 2 months — during a tax year are not treated as special temporary permits. At that point the permitted weight can matter.
Set up your business once; every truck and every later return starts from it.
From weight to category
Once you have the number, match it to a category on the IRS table. Category A is 55,000 lb, each category above it covers the next 1,000 lb, and category V is anything over 75,000 lb. The full table with standard and logging rates is on the Form 2290 rates page, and the weight categories guide explains each band.
If the weight later goes up — a heavier maximum load customarily carried, for example — and the truck moves into a higher category, you file an amendment for the weight increase and pay the difference for the rest of the period.
Filing it
On the return, each truck gets its VIN and its category. Fleets can put the category in a spreadsheet column and import every truck at once. New to filing? The step-by-step guide to filing Form 2290 online walks through each truck in order.