§ 3509. Determination of employer’s liability for certain employment taxes
(a)
 In general 
If any employer fails to deduct and withhold any tax under chapter 24 or subchapter A of chapter 21 with respect to any employee by reason of treating such employee as not being an employee for purposes of such chapter or subchapter, the amount of the employer’s liability for—
(1)
 Withholding taxes 
Tax under chapter 24 for such year with respect to such employee shall be determined as if the amount required to be deducted and withheld were equal to 1.5 percent of the wages (as defined in section 
3401) paid to such employee.
(b)
 Employer’s liability increased where employer disregards reporting requirements 
(1)
 In general 
(2)
 Applicable requirements 
For purposes of paragraph (1), the term “applicable requirements” means the requirements described in paragraph (1) which would be applicable consistent with the employer’s treatment of the employee as not being an employee for purposes of chapter 24 or subchapter A of chapter 21.
(c)
 Section not to apply in cases of intentional disregard 
This section shall not apply to the determination of the employer’s liability for tax under chapter 24 or subchapter A of chapter 21 if such liability is due to the employer’s intentional disregard of the requirement to deduct and withhold such tax.
(d)
 Special rules 
For purposes of this section—
(1)
 Determination of liability 
If the amount of any liability for tax is determined under this section—
(2)
 Section not to apply where employer deducts wage but not social security taxes 
This section shall not apply to any employer with respect to any wages if—
(3)
 Section not to apply to certain statutory employees 
This section shall not apply to any tax under subchapter A of chapter 21 with respect to an individual described in subsection (d)(3) of section 
3121 (without regard to whether such individual is described in paragraph (1) or (2) of such subsection).
[1] So in original. Probably should be “section”.