If you receive a Final Notice of Intent to Levy, you need to call a tax professional immediately.
The final notice of intent to levy will be accompanied by a notice of a right to a Collection Due Process Hearing (or CDP). There will be a Form 12153 which allows you to request a CDP. You have thirty (30) days of hands-off time from the IRS in which they cannot levy. If you are outside thirty days, you can still request a hearing, what the IRS calls an "Equivalency Hearing."
Here are the advantages of requesting a CDP. First, the IRS must issue a Final Notice of Intent to Levy, except in very rare circumstances too narrow to discuss here, in order to start levying your bank accounts, wages or other property. The IRS sometimes makes mistakes on this. If they levy and fail to give the final notice, the property is going to be returned to you. Second, you can discuss any collection alternatives that may be available to you at the CDP. The CPD is technically an appeal with the IRS, and their focus is on making sure that their levy procedures are warranted. However, you will have your CDP Officer's attention to discuss installment agreements, extensions of time to pay, offers in compromise, hardship status, penalty and interest abatement and innocent spouse relief. You need to have a plan of action ready to present and your documentation in order. Finally, and perhaps most importantly, a timely CDP request will stop collection activity until the hearing occurs. I recommend sending your request certified mail, as the request must be postmarked within 30 days of its issuance date. CDP's rarely occur quickly. They often take 4-6 months to schedule and occur. Often, this is just enough time to get funds together to round up money to full pay the debt.
Here are the negatives and pitfalls to the CDP request. First, requests for a hearing made outside 30 days DO NOT STOP COLLECTION! You could be timely on the request based on the final notice they send you, but you could have other tax periods with liabilities for which the IRS has already sent you a final notice of intent to levy. The IRS just has to send the notices to your last known address. If you have moved or failed to pick up your certified mail, the IRS just has to make an attempt to mail it. Finally, the IRS' statute of limitation or CSED is tolled (or stopped) during the pendency of your request for CDP, plus 90 days. If you are getting really close to a statute of limitations running out on the IRS for a given liability, there is no reason to slow down the statute for the IRS.
I recommend that you not make these types of decisions without advance planning and tax representation. A tax professional is able to read your master tax file with the IRS and strategically outline a course of action that will navigate you through this minefield. I always remark to potential clients that once a levy hits, your options get more and more limited because the IRS is taking the money you need to defend yourself and so the vicious cycle continues.