If you send the IRS 20% of your gross business earnings *right now*, that will reduce your underpayment penalties that are accumulating, and will prevent (or at least reduce) the amount of paperwork you will be doing to claim exemption from those penalties, if they are in fact, assessed. If your state also taxes personal income, then don't forget about quarterly taxes to your state too.
http://www.irs.gov/directpay for the federal taxes.
