That's a great question — and that is one of the first issues (alongside bitcoin) that we want to get right.
Garnishments, withholdings, and taxes vary state to state, and sometimes city by city. We're working with our tax lawyers and accountants to make this all seamless, but it's a real pain. We're looking to launch in potentially three states at first — just to make things easy.
Right now the reporting and payments are manual — we notify the company how much is owed in taxes etc. and they must pay the government themselves.
We're looking to simplify this further, though, and debit the money for garnishments to pay the government on behalf of employers where possible.