### Question
How does the law define underpayment?


### Answer
Under *26 U.S.C. § 6664*, **underpayment** is defined as:

> the amount by which any tax imposed by this title exceeds the excess of—



(1) the sum of—



(A) the amount shown as the tax by the taxpayer on his return, plus



(B) amounts not so shown previously assessed (or collected without assessment), over


  


(2) the amount of rebates made

#### Citation:
  - *26 U.S.C. § 6664*
  - Heading: **Subtitle F-Procedure and Administration > CHAPTER 68-ADDITIONS TO THE TAX, ADDITIONAL AMOUNTS, AND ASSESSABLE PENALTIES > Subchapter A-Additions to the Tax and Additional Amounts > PART II-ACCURACY-RELATED AND FRAUD PENALTIES**

