If you owe money on a judgment and the judgment is valid, the creditor can levy your account as you have seen. If you deposit funds into the account (from where ever including your tax refund) they could take it if they levy the account at the right time. I would advise that you don't have the tax refund deposited into that account or any account for that matter.
This is not legal advice nor intended to create an attorney-client relationship.
Usually, it is "anything above $400" or something similar because they use a means test. The refund will likely be considered money you have in excess of your living expenses, and will be taken.
The creditor can levy on your account once it is deposited.
Any individual seeking legal advice for their own situation should retain their own legal counsel as this response provides information that is general in nature and not specific to any person's unique situation. Circular 230 Disclaimer - Advice given in this response cannot be used to eliminate penalties with the IRS or any other governmental agency.