I live in McKinney and have been looking at this situation from a similar perspective. We bought our home here in 2000. Property taxes stayed pretty flat until the past few years. It is my understanding that the maximum a person's homestead taxes can be raised is 10% per year- Texas state law.
I'm with you. I don't think we're in a bubble. So I've been doing some extrapolation. I assumed a 10% yearly increase in property taxes (you've done the math, seriously, I'm grateful it's 9% and not 10), applied the rule of 72 and have realized that in about 7 years, my property taxes will double. We're a little above $5,000 for 2016, so a $10,000 property tax bill is significant in my opinion. The good news is, if the property tax continues on its trajectory, it's because property values are increasing. I still believe that relative to national averages, and certainly places like California (average home price $448,000 versus $146,100 in Texas), we have PLENTY of room for appreciation- especially in the north Dallas area. As you noted, the market will equalize, at least to some degree.
At some point, market forces are going to scream at those of us in the DFW area- SELL! When a bubble finally does form, and our house that is now worth about around $250,000 goes to.... who knows, but I'm guessing somewhere from $500-$700K, I've already told my wife. We WILL sell our primary residence. The question in my mind is, what about rental properties? We're currently at 8 rental units. I don't know if we'll sell everything, but I truly do believe at some point, north Dallas, if not north Texas or more of Texas, will in fact have a bubble form and we as investors need to think of an exit strategy not only for our personal residences but investment properties as well.
I am originally from California. A very dear friend owns and lives in a 1960s middle class 3/2/2, around 1,600 s.f. I forget the year (I think it was around 2007), but his realtor friend told him he could get $550,000 for that house in a week. To me, that is a classic SELL signal- a ridiculous price available quickly Of course, it also depends on other factors in the market at the time. That said, we're all aware of the California bubble. He regrets not selling. He could have taken the $550,000 and bought a similar (if not the very same home!) home a few years later for $250,000.
This leads me back to your main point- the role of property taxes in forming a bubble. I think it's significant. I am certainly no expert and haven't quite figured out how that brings a halt to the market. But I think we both (and probably others here) can agree it will be a factor.
Furthermore, I ponder how this affects investors. Example: we bought a duplex in the Fort Worth area. Tarrant County is proposing an over 50% property tax increase! The new assessment would be $30,000 more than our purchase price and $15,000 more than the value appraised at the time of purchase. I submitted a two-tiered protest, using of course the purchase price as the first line of defense and the appraisal as the second. We'll see how that goes.
The point of this bit of a tangent is, what will be the market rent increases be in comparison with property tax increases? My guess is over the long haul, property tax increases will outpace market rent increases. So how will that affect the investment property market, when looking at it through the lens of purchase price, possible diminishing monthly income and increase in values. That's a tough prediction to make- especially given how in a city like McKinney you can forget the 1% rule for rentals as pretty much impossible, while in the Tarrant County I wouldn't touch anything that wasn't significantly above the 1% rule- 1.4% or better is my preference.
Anyway, excellent topic and can of worms you've opened up here. I look forward to more people's thoughts on this.