> properties have a 'Council Tax Band' which is the equivalent of your property taxes but it is assessed once.
PAID every year, I assume? (Or monthly installments in Wirral.)
Wirral Council Tax bands 2016-2017
Band Property values 2016-17
A Up to £40,001 £1,043.29
B £40,000 - £52,001 £1,217.18
C £52,000 - £68,001 £1,391.06 . . . . .
"Council Tax you pay depends on how much the property was worth on 1st April 1991."
In much (not all) the US, they used to use old-old appraisals. A $100K house might be on the rolls as $12K (in 1955). (Of course the tax rate was computed to cover the municipal budget, regardless how old and un-inflated the appraisal was.)
In our flimsy knock-down / add-on construction, actual value would change radically over the decades, and not uniformly across all properties in town. Old appraisals (corrected for inflation) began to diverge wildly from actual current sale prices. Some folks felt they were over-charged relative to now-nicer homes in the same area. They sued.
In the few states I know, the Tax must be based on Current Market Value supported by recent appraisal. The over-taxed NJ town I moved out of was doing this. Nominally they want to walk-through and count the toilets and grade the floors and wallboard. Square foot inside and acres outside go to a formula. Here there is a stiff factor for Water View.
> It does not seem to matter what you do to the property thereafter
I would assume if you bought a 3-room shack, and built a 5-storey hotel or office of 20X floor area, they would want to raise the tax. Wal-Mart bought an empty field worth maybe $5K of tax, and now pays >$500K tax (and whines about it).
The guy we bought this shack from was not taking care of business. We appealed our appraisal on the grounds it was very run-down, and our open-market price-paid was 3/4 of what it was appraised. A guy came out to see, and knocked some $K off the appraisal. We then added-on a living room and built a garage, with Permits, and that data was added to our appraisal. (We ended up paying more, but living better, and as fairly appraised as we should expect.)
Appraisals are dated, and each year an average market factor is applied to reflect how "all" prices have moved up (1990s) or down (2009). That's the big number on our bill.
The tax is computed by "mil rate", essentially a fraction of the value. This varies, because in recent years valuations have been up/down while town budgets just grow slowly. The actual tax does not vary near as much, mostly rises a tolerable small amount every year.
