### Question
How is the "petroleum residue" defined?


### Answer
The term **petroleum residue** is defined in *26 U.S.C. § 48B* as follows -

> the carbonized product of high-boiling hydrocarbon fractions obtained in petroleum processing

#### Citation:
  - *26 U.S.C. § 48B*
  - Heading: **Subtitle A-Income Taxes > CHAPTER 1-NORMAL TAXES AND SURTAXES > Subchapter A-Determination of Tax Liability > PART IV-CREDITS AGAINST TAX > Subpart E-Rules for Computing Investment Credit**

