Apparently I could not read the font to complete the register verification, so I was not able to complete the registration process.

My question is this: I was taken to court for an unpaid emergency room bill and there is now a judgement against me. Can they garnish my federal tax return for this bill?

No, but once its deposited they can attach your bank account.

Actually, if it is a valid debt, the tax refund CAN be attached by petitioning the federal courts.

But it is so cumbersome that most bill collectors will not bother, as garnishing wages or attaching a bank account is MUCH simpler.