Local government should be under a requirement to pay 90% of the assessed value to the owner with "here's the keys" clause.
After all, they could make their money back plus the 10%, couldn't they?
The market value in Florida is computed for the time 10 months before the tax bill comes.
The best check on the tax assessor’s work is probably houses listed for sale as of January 1 that sell shortly afterward.
The real estate industry price is only normally obtainable with professional help, so my tax assessor uses about a 12% reduction for commissions, mortgage points and other seller-> buyer help.