The procedures for garnishing wages due to unpaid taxes and due to unpaid federal student loans are quite similar. Note that in most tax cases, and (it appears) in all student loan cases, you have a right to a hearing to argue against the garnishment.
From IRS Publication 594, page 6:
If you don’t pay your taxes (or make arrangements to settle your debt), we could seize and sell your property. We will not seize your property to collect an individual shared responsibility payment. We usually seize only after the following things have occurred.
- We assessed the tax and sent you a bill,
- You neglected or refused to pay the tax, and
- We sent you a Final Notice of Intent to Levy and Notice of Your
Right to a Hearing at least 30 days before the seizure.
However, there are exceptions for when we don’t have to offer you a hearing at least 30 days before seizing your property. These include situations when:
- The collection of the tax is in jeopardy,
- A levy is served to collect tax from a state tax refund,
- A levy is served to collect the tax debt of a federal contractor, or
- A Disqualified Employment Tax Levy (DETL) is served.
You can request a Collection Due Process hearing within 30 days from the date of your Notice of Intent to Levy and Notice of Your Right to a Hearing. Send your request to the address on your notice. For more information, see Form 12153, Request for a Collection Due Process or Equivalent Hearing. At the conclusion of your hearing, the Office of Appeals will provide a determination. You’ll have 30 days after the determination to challenge it in the U.S. Tax Court. If Collection Due Process rights aren’t available for your case, you may have other appeal options, such as the Collection Appeals Program.
Federal student loan procedure:
From the website of the Federal Student Aid office:
With garnishment, you have the right to:
- be sent a notice that explains ED’s [the US Dept. of Education's] intention to garnish your wages in 30 days, the nature and amount of your debt, your opportunity to inspect and copy records relating to your debt, your right to object to garnishment, and your option to avoid garnishment by voluntary repayment;
- be given an opportunity to enter into a written agreement under terms agreeable to ED to establish a voluntary repayment agreement;
- be given an opportunity for a hearing to present and obtain a ruling on
- any objection you have to the existence, amount, or enforceability of the debt;
- any objection that garnishment of 15 percent of your disposable pay would produce an extreme financial hardship; or
- any objection stating that garnishment cannot be used at this time because you’ve been employed for less than 12 months after having previously been involuntarily separated from employment;
- have the garnishment action withheld by filing a timely request for a hearing, until the hearing is completed and a decision issued; ...
For student loan garnishments, there do not appear to be exceptions for the right to a hearing (in contrast to the exceptions that exist for certain IRS garnishments.) It also does not appear that there is an equivalent of the U.S. Tax Court, to which one can appeal the result of the initial hearing.