The tax imposed by section 3101 shall be collected by the employer of the taxpayer, by deducting the amount of the tax from the wages as and when paid. An employer who in any calendar year pays to an employee cash remuneration to which paragraph (7)(B) of section 3121(a) is applicable may deduct an amount equivalent to such tax from any such payment of remuneration, even though at the time of payment the total amount of such remuneration paid to the employee by the employer in the calendar year is less than the applicable dollar threshold (as defined in section 3121(x)) for such year; and an employer who in any calendar year pays to an employee cash remuneration to which paragraph (7)(C) or (10) of section 3121(a) is applicable may deduct an amount equivalent to such tax from any such payment of remuneration, even though at the time of payment the total amount of such remuneration paid to the employee by the employer in the calendar year is less than $100; and an employer who in any calendar year pays to an employee cash remuneration to which paragraph (8)(B) of section 3121(a) is applicable may deduct an amount equivalent to such tax from any such payment of remuneration, even though at the time of payment the total amount of such remuneration paid to the employee by the employer in the calendar year is less than $150; and an employer who is furnished by an employee a written statement of tips (received in a calendar month) pursuant to section 6053(a) to which paragraph (12)(B) of section 3121(a) is applicable may deduct an amount equivalent to such tax with respect to such tips from any wages of the employee (exclusive of tips) under his control, even though at the time such statement is furnished the total amount of the tips included in statements furnished to the employer as having been received by the employee in such calendar month in the course of his employment by such employer is less than $20.
Every employer required so to deduct the tax shall be liable for the payment of such tax, and shall be indemnified against the claims and demands of any person for the amount of any such payment made by such employer.
To the extent that the amount of any tax imposed by section 3101(b)(2) is not collected by the employer, such tax shall be paid by the employee.
If an employer, in violation of this chapter, fails to deduct and withhold the tax imposed by section 3101(b)(2) and thereafter the tax is paid by the employee, the tax so required to be deducted and withheld shall not be collected from the employer, but this paragraph shall in no case relieve the employer from liability for any penalties or additions to tax otherwise applicable in respect of such failure to deduct and withhold.