In determining the amount of pay subject to garnishment under this part, there shall be excluded amounts which:

Are owed by the employee-obligor to the United States;

Are required by law to be deducted from the employee-obligor's pay, including, but not limited to amounts deducted in compliance with the Federal Insurance and Contributions Act (FICA), including amounts deducted for Medicare and for Old Age, Survivor, and Disability Insurance (OASDI);

Are properly withheld for Federal, State, or local income tax purposes, if the withholding of the amounts is authorized or required by law and if amounts withheld are not greater than would be the case if the employee-obligor claimed all dependents to which the employee-obligor were entitled. The withholding of additional amounts pursuant to section 3402(i) of title 26 of the United States Code may be permitted only when the employee-obligor presents evidence of a tax obligation which supports the additional withholding;

Are deducted as health insurance premiums;

Are deducted as normal retirement contributions, not including amounts deducted for supplementary coverage. For purposes of this section, all amounts contributed under sections 8351 and 8432(a) of title 5 of the United States Code to the Thrift Savings Fund are deemed to be normal retirement contributions. Except as provided in this paragraph, amounts voluntarily contributed toward additional retirement benefits are considered to be supplementary;

Are deducted as normal life insurance premiums from salary or other remuneration for employment, not including amounts deducted for supplementary coverage. Federal Employees' Group Life Insurance premiums for “Basic Life” coverage are considered to be normal life insurance premiums; all optional Federal Employees' Group Life Insurance premiums and any life insurance premiums paid for by allotment are considered to be supplementary.

Amounts withheld in compliance with legal process based on child support and/or alimony indebtedness are not exclusions.