If legal in your state, tax returns can be garnished for a car loan—but only if the vehicle has already been repossessed and sold for less than your outstanding loan balance. Your tax return (or wages) could be used to cover the deficiency between what you owe and the vehicle’s selling price.
However, because the vehicle hasn’t been repossessed, you should inform the lender of your situation before you miss a payment. More often than not, your lender will be understanding and help you find a solution, such as modifying the loan, deferring payment, or refinancing into a loan that better suits your current financial situation.