As with most answers in the law, this depends.
If you are receiving SSDI, it may be garnished if you owe money to the government. This could be for back taxes or federal student loans, or even for child support and alimony. Additionally, any fines imposed as a result of federal criminal proceedings can also be garnished. Types of money or debts that cannot be garnished include debt owed to private companies like credit cards, car loans, and medical expenses.
On the other hand, if you are receiving SSI disability, your benefits generally cannot be garnished. This is because SSI disability is not considered wages, but instead is meant to support a low-to-no income individual with the basics of food and shelter. However, there may be exceptions for alimony or child support.
If your disability benefits ARE garnished, and your sole source of income is either SSDI or SSI, you will need to provide evidence proving this. You may have to appear in Court to fight the garnishment because not all banks follow the rule that the source of funds must first be verified before paying a garnishment. This can result in your benefits being taken and held temporarily until you can obtain an order for refund from the Court.