They may crack down and use the IRS requirement (and IMO probably will, since it is the most handy definition to hang a hat on) or it might be an existing state statute if one exists or what is deemed reasonable by the local HUD authorities/Prosecutors.

Thanks Bill...Do you know how one would go about looking up said statutes without paying an attorney for advice?

I looked at the Florida landlord/tenant statutes and it isn't mentioned.

This was explained to her, that she does not need to leave the property and that the investor that purchases it will want her to stay, but she is uncooperative.Florida Statute says we need to send a letter stating she needs to "cure" this issue within 7 days or else we can begin the eviction process.

Even consider offering a month to month leaseI'm not sure what statute you're basing this on, but that's not true.

In my state (PA), the estate will advertise in a newspaper of general circulation and in the law reporter type newspaper; this is to get the statute of limitations rolling so that claims on the estate expire after some specified amount of time after the ads run.

There are only a few states that have land trust statutes on the books, several states that don't have statutes but DO recognize land trusts from other states, and then some (like my state of TN) that do not recognize land trusts at all.

In PA the requirement for Adverse Possession is 21 years so if you buy at Tax Sale and hold for 21 years in PA, you can then claim Adverse Possession and the statute of limitations for appealing the Tax Sale has expired. 

You want a solid proof that the FTB is correct, or otherwise you will feel they are robbing you, and there is some way around it.As I mentioned previously, my personal layman's reading of the CA statute makes me believe that the FTB is overreaching in their stance.

One additional note, all of the rules of Florida relating to tax deed auctions are mandated by statute, so the same rules in your county will apply throughout the state.