31 CFR §215.11

1. (a)To require collection by agencies of the United States of delinquent tax liabilities of Federal employees or members of the Armed Forces, or
2. (b)To consent to the application of any provision of law of the State, city or county which has the effect of:
   1. (1)Imposing more burdensome requirements upon the United States than it imposes on other employers, or
   2. (2)Subjecting the United States or any of its officers or employees to any penalty or liability, or
3. (c)To consent to procedures for withholding, filing of returns, and payment of the withheld taxes to a State, city or county that do not conform to the usual fiscal practices of agencies, or
4. (d)To permit withholding of a city or county tax from the pay of a Federal employee who is not a resident of, or whose regular place of Federal employment is not within, the State in which the city or county is located, unless the employee consents to the withholding, or
5. (e)To permit the withholding of city or county income or employment taxes from the pay of members of the Armed Forces of the United States, or
6. (f)To allow agencies to accept compensation from a State, city or county for services performed in withholding of State or city or county income or employment taxes.