### Question
How does the law define base period?


### Answer
Under *26 U.S.C. § 41*, **base period** is defined as:

> the 3-taxable-year period ending with the taxable year immediately preceding the 1st taxable year of the taxpayer beginning after December 31, 1983

#### Citation:
  - *26 U.S.C. § 41*
  - Heading: **Subtitle A-Income Taxes > CHAPTER 1-NORMAL TAXES AND SURTAXES > Subchapter A-Determination of Tax Liability > PART IV-CREDITS AGAINST TAX > Subpart D-Business Related Credits**

