Florida doesn't have a "tools of trade" exemption like some states. You should speak with a bankruptcy attorney to see if there is a way to protect the truck.
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Unfortunately, there are no exemptions in Florida for tools of trade, or a motor vehicle for work, beyond the $1,000.00 motor vehicle exemption under Florida Statute 222.25(1). If the vehicle is owned by a corporation, or LLC that is controlled by you, the trustee would need to take the stock of the business and may look twice to be sure that there are not any liabilities that would make taking the semi unattractive. However, if it is simply in your name, it is fair game for the trustee.
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No tools of trade exemption in Florida. Please speak with a qualified bankruptcy in your area to see what other exemptions can be used.
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The short answer is "No." Florida does not have an exemption allocated to work vehicles. It does not matter how much you depend upon a car to work or to get to work. If your family had a lien on your title when they made the loan, that lien would protect the vehicle. Don't try to put the lien on now- it won't work in bankruptcy. But, if you recorded the vehicle lien when they loaned you the money the work vehicle may be protected (depending on value etc).
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Unfortunately in Florida the exemption amount on a vehicle is $1000. However, if you are eligible to take a wild card exemption [if you do not have a homestead] you may use all of the $4000 that is available to you towards your vehicle. I have done that many times in the Southern District of Florida.