Questionable charges: equipment, fuel, and other line items to question

A contractor’s price has two honest parts: the cost of doing your job, and their profit for doing it well. Questionable charges live in the gap — costs that were already baked into the bid showing up again as separate line items, or fees priced far above what they actually cost. Everything here matters double on cost-plus contracts, where every invoice flows straight to your bill.

None of these are automatically dishonest. Every one of them is a fair question. A contractor with a clean bid will answer without flinching; a contractor who gets defensive about a line item is telling you what’s in it.

Equipment charges: are you renting their own tools?

Renting a true specialty machine — an excavator, a crane, a concrete pump — is a real, passable cost. But some invoices charge daily “equipment rental” for tools the contractor owns and uses on every job: their truck, their compressor, their saws. That’s overhead, and overhead belongs inside the bid price, not billed back to you a second time.

The test is simple: ask whether the equipment was rented from a third party, and if so, ask to see the rental receipt. Owned equipment billed at rental-yard day rates is the single most common form of invoice padding we see.

The vague-fee family

“Mobilization.” “Fuel surcharge.” “Shop fee.” “Job supervision.” Each can be legitimate — mobilizing real heavy equipment costs real money — but as round, unitemized numbers they’re a place to park padding. A $1,500 mobilization fee on a job with no heavy equipment is a question that deserves a specific answer.

Supervision is the subtle one: on a fixed-price job, supervising the work is the contractor’s job — it’s what the price is for. A separate hourly supervision line on top of a fixed price is usually double-billing.

Markup and the time-and-materials trap

A 10–20 percent markup on materials and subcontractors is normal — it covers procurement, warranty, and coordination. The contract should state the percentage; a stated markup is a markup you can check.

Watch for this

Double markup: margin stacked on margin

A sub bills the GC $10,000 — with the sub’s own profit already inside. The GC adds 20 percent and bills you $12,000, then adds a “project management” fee on top of that. Each line looks reasonable alone; together, you’re paying margin on margin on the same work.

One question defuses it: “Is your markup applied to the sub’s invoice as billed — and is anything else added on top of it?” Get the answer reflected in the contract.

The other place markup hides is “time and materials” billing where you never see the underlying receipts. On any T&M work, the contract should give you the right to see invoices and timesheets on request — a contractor billing honestly has no reason to refuse.