Property tax in vietnam

As far I know, there is a tax band/class for each area which differs in something like main road/side road, distance some localities, like near airport/central city  =  base/ theoretical market value per meter land and usage right, and another part of the tax is the building itself as well as the purpose. I understand that here are many allowances possible.

A few years ago, this where 2 kind of taxes, same as the so called red books, this has be joined about 3 years ago - maybe this is the "new rule" you are mention.  Many books are still being processed and someone getting it now, might call it "new" ? Or about the same time, a tax is applied, when selling property at a higher price than the purchase; this is born by the seller.

I know someone, who had an estimate of taxes prior building and as soon building was finished, taxes where in excess of 500% the previous estimate.  However, due to language issues, it was not clear to make out, if there old outstanding taxes on the land and  other things.

Property/taxes are like black boxes, you never will know exactly how it's calculated and the next year, it might change again, if the first calculation was not right.