Here check this out:
Why is your employer “Withholding” your wages?
IRS Reg. 31.3402(f)(2)-1(a) stipulates that if an employee fails or refuses to file a valid W-4, withholding should be as if the employee were single
with 0 allowances. See also:
TITLE 26 > Subtitle C > CHAPTER 24 > § 3401
TITLE 26—INTERNAL REVENUE CODE
Subtitle C—Employment Taxes
CHAPTER 24—COLLECTION OF INCOME TAX AT SOURCE ON WAGES
§ 3401. Definitions
(e) Number of withholding exemptions claimed
For purposes of this chapter, the term “number of withholding exemptions claimed” means the number of withholding exemptions claimed in a
withholding exemption certificate in effect under section 3402 (f), or in effect under the corresponding section of prior law, except that if no such
certificate is in effect, the number of withholding exemptions claimed shall be considered to be zero.
URL:
www4.law.cornell.edu...
TITLE 26 > Subtitle C > CHAPTER 24 > § 3401
TITLE 26—INTERNAL REVENUE CODE
Subtitle C—Employment Taxes
CHAPTER 24—COLLECTION OF INCOME TAX AT SOURCE ON WAGES
§ 3401. Definitions
(c) Employee
For purposes of this chapter, the term “employee” includes an officer, employee, or elected official of the United States , a State, or any
political subdivision thereof, or the District of Columbia , or any agency or instrumentality of any one or more of the foregoing. The term
“employee” also includes an officer of a corporation.
URL:
www4.law.cornell.edu...
TITLE 26 > Subtitle C > CHAPTER 21 > Subchapter C > § 3121
TITLE 26—INTERNAL REVENUE CODE
Subtitle C—Employment Taxes
CHAPTER 21—FEDERAL INSURANCE CONTRIBUTIONS ACT
Subchapter C—General Provisions
§ 3121. Definitions
(h) American employer
For purposes of this chapter, the term “American employer” means an employer which is—
(1) the United States or any instrumentality thereof,
(2) an individual who is a resident of the United States ,
(3) a partnership, if two-thirds or more of the partners are residents of the United States ,
(4) a trust, if all of the trustees are residents of the United States , or
(5) a corporation organized under the laws of the United States or of any State.
URL:
www.law.cornell.edu...
(e) State , United States , and citizen
For purposes of this chapter—
(1) State
The term “State” includes the District of Columbia , the Commonwealth of Puerto Rico , the Virgin Islands, Guam, and American Samoa .
(2) United States
The term “United States ” when used in a geographical sense includes the Commonwealth of Puerto Rico , the Virgin Islands, Guam, and American
Samoa .
An individual who is a citizen of the Commonwealth of Puerto Rico (but not otherwise a citizen of the United States ) shall be considered, for
purposes of this section, as a citizen of the United States .
URL:
www.law.cornell.edu...