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Ezel / Tax Rulings / TX
TX 7908L2023D05 Motor Vehicle Tax 1979-08-16

Was a drilling rig permanently mounted on a truck taxable as a motor vehicle or movable specialized equipment?

Short answer: The truck-mounted rig was a motor vehicle. A truck remained subject to motor vehicle tax despite attached drilling accessories or limited highway use. By contrast, a mobile drilling rig constructed as one integrated specialized unit would be movable specialized equipment subject to regular state and city limited sales tax. Construction method, not merely function, produced the different result.

Apply this to your situation

This page answers the general question as of 1979. Ezel answers yours, under current Texas tax law, with citations.

Currency note: this ruling is from 1979
Subsequent statutory amendments, regulation changes, court decisions, or later rulings may have changed the analysis. Treat this page as historical context, not current tax advice. Verify current law before relying on any specific rule, rate, or position mentioned here.
Disclaimer: This is an August 16, 1979 taxpayer-response letter relying on photographs and details not reproduced in STAR and former Rule .040. Current movable-specialized-equipment, truck, accessory, highway-use, drilling-rig, state and local sales tax, and registration rules may differ. Two units serving the same purpose can classify differently based on construction. STAR documents may no longer represent current policy even when not marked superseded. Taxpayer details are redacted. This summary is informational only and is not legal or tax advice.
About this page: The plain-English summary, reader guidance, and Q&A below were written by Ezel based on the official state tax ruling. The original ruling (linked on this page) is the authoritative source for any reliance.

Plain-English summary

A drilling rig permanently mounted on an International truck remained a motor vehicle and was correctly taxed at registration. Attached accessories and limited highway use did not change the truck's classification.

A mobile drilling rig constructed from the outset as one integrated specialized unit would instead fall under Limited Sales Tax, including state and city tax under the historical guidance.

What this means for you

Function alone did not control. Construction and attachment to an existing motor vehicle changed the tax category.

Common questions

Q: Did the attached rig turn the truck into specialized equipment?
A: No.

Q: Could a one-piece mobile rig classify differently?
A: Yes.

Citations and references

  • Former Motor Vehicle Sales and Use Tax Rule .040

Source

Original ruling text

August 16, 1979

Dear ***:

I appreciate your sending me photographs and a more complete description
of your drilling rig.

Based on this additional information, it appears that motor vehicle tax
was properly paid at the time you registered this unit.

Your drilling rig is permanently mounted on an International Truck. A
truck is a motor vehicle, and remains taxable as a motor vehicle regardless
of any accessories that are attached to it, even though the accessories
attached may mean that the vehicle's highway use is limited.

I have enclosed a brochure on moveable specialized equipment and a copy
of Motor Vehicle Sales and Use Tax Rule .040, both of which discuss just
this type of situation.

There is some confusion surrounding this issue - because two units which
are used for the same purpose may be taxed differently, depending on how
the units were actually built. If you purchased a mobile drilling rig that
was constructed as one unit, then the unit would be taxed under Limited
Sales Tax, the regular state and city sales tax.

I hope this explains why you were charged the correct tax when you
registered your drilling rig. Again, I thank you for sending photographs
so that we could make a definite determination.

If you have any other motor vehicle sales tax question, please write the
Motor Vehicle Sales Tax Division or call 1-800-252-5555 toll-free from
anywhere in Texas.

Sincerely,

Victoria Bailey
Motor Vehicle Sales Tax

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