No they cannot. They cannot withhold the fees from your pay, as Washingon statutes are very strict about what can be deducted from your pay, and something like this is not on the list. Only if you wilfully caused damage to your employer can they demand compensation from you. And there is no other basis for the employer to hold you accountable for their own negligence.
Your employer has a decent chance of setting aside the judgment if they can show the failure to return the documents was a good faith error, in this case, they claimed they returned them, but they were not received.
This would seem to be a violation of the Fair Labor Standards Act as well as possibly state wage statutes in the state where you work. You should consult with a local attorney as I am a NJ attorney. Each state may have state regulations which offer certain protections as well. Best wishes.
Until you come in for a consultation, please be advised that you are not considered a client of the firm and no attorney client relationship is established. Thus, this email is not to advise you of any legal rights but merely to advise of a general response to your posting. Also, please note that I am a NJ lawyer and you should ensure that before you take action, you consult with an attorney licensed to practice in the jurisdiction where you reside. This way, you can have the benefit of someone who is familiar with case law and statutes particular to your state as well as someone who can discuss your matter in more full detail as well as review documents.
If an employer fails to answer a wage garnishment, they are the ones that are liable. As long as you were not the cause of the answer not being sent in, you are not responsible for it.
Legal disclaimer: The answer provided: A) is for informational purposes only, B) is not intended to constitute legal advice, C) should not be relied upon in lieu of consultation with an attorney, and, D) does not establish an attorney client relationship. The answer may be different if all of the facts were known.