There is a bit of regressiveness to this though, as it will be worth it for people with a lot of property to pay someone to regularly update their assessed value to keep pace with the market, while those with less property will probably just set a large premium and update infrequently. This is a problem with pretty much any tax though; the more you are being taxed, the more you can afford to pay to figure out how not to be taxed.

I posted potential problems in my sibling comment earlier, but as far as this goes, the ugliest thing would be e.g. an 80 year old who forgot to update their assessed value in a hot market being kicked out by someone who bought their property to flip it for 2x the assessed value.

In theory, they are a tax-cheat who got what they deserved...

I suppose the free-market solution would be services that assess your home for a fee; they could provide insurance against undervaluation as well to incentivize them to do the right thing. This monetarily works out to be roughly equivalent to the government paying private companies to fairly assess people's home-values, but with financial incentives for doing it properly.

This seems a bit unlikely to me since you're directly raising your taxes by doing this. I'd expect the opposite, most people undervaluing their house on the assumption that "it won't happen to me". Also, if I bought for $200k 10 years ago then it can't possibly access for $450k today right? People don't have a good grasp on how fast a market can inflate given the conditions.

I would expect a lot more anti-tax guys who access their property at $1 and if someone comes up to take it they pull out their shotgun.

For this to work at all the government would have to provide a minimum and possibly maximum based on traditional assessments. Basically the system we have now except that you can say that you've done some work to spruce up your house so it's worth more and you like paying more taxes. But it also has the "feature" where you can be evicted by a person with money at any time. Can you imagine this in Silicon Valley? Old people being kicked out of their home by tech-bros would be a daily story.

> This seems a bit unlikely to me since you're directly raising your taxes by doing this. I'd expect the opposite, most people undervaluing their house on the assumption that "it won't happen to me". Also, if I bought for $200k 10 years ago then it can't possibly access for $450k today right? People don't have a good grasp on how fast a market can inflate given the conditions.

1. You're not supposed to set it at a price that the house is worth on the market, you're supposed to set it at the price that would make you willing to move. That requires a premium, because moving is a hassle and isn't free. Because of this a revenue-neutral version is coupled with a commensurate lowering of rates.

2. "it won't happen to me" will go away really quickly if people are undervaluing properties, because it will happen to everybody. Look at the people investing in properties now where they must pay market value; imagine if people can invest in properties for below market value. As with most radical change the period of transition will be terrible

> I would expect a lot more anti-tax guys who access their property at $1 and if someone comes up to take it they pull out their shotgun.

I'm not sure how that's different from them not paying their taxes at all and pulling out their shotgun when the government forecloses on them? It's not like a guy walks up with a $1 bill and says "now leave." Evictions would happen in the same manner they do now, and deed transfers are recorded in a notary's office, not on the property itself.

> For this to work at all the government would have to provide a minimum and possibly maximum based on traditional assessments. Basically the system we have now except that you can say that you've done some work to spruce up your house so it's worth more and you like paying more taxes. But it also has the "feature" where you can be evicted by a person with money at any time.

I see lots of problems with this system, but approximately zero of them are fixed by the government providing a valid range. That defeats the entire purpose of the system to be self-enforcing. One possible fix is rather than an automatic transfer, the owner could agree to a back-reassessment, combined with penalties. The penalties could be split between the government and "purchaser," as payment for their services.

> Can you imagine this in Silicon Valley? Old people being kicked out of their home by tech-bros would be a daily story.

This assumes either:

1. Old people don't follow the news or are too stupid to act on the news (it's a daily story and yet they don't bother to address it themselves?)

2. Old people can't afford the property tax on their house

Maybe you actually think #1. I think it will be much less frequent than daily; there's a certain point at which people are both afraid of something and yet some fraction neglect to take action on it (think deadly crashes from drunk driving or texting), which is probably the equilibrium we will reach. Again, an automated service that keeps your assessment in line with the market is an obvious offering here.

If you think #2, then this is why Proposition 13 was passed over 40 years ago, and that proposition seems to have popular support still. Economists question the need for a retired widow to live by themselves in a $2.5M 4 bedroom in Cupertino, but that of course neglects human factors like "I lived with my husband in this house for 30 years, and raised my kids here, won't you please let me live my last few years here?"

I think the last point is a disconnect between what is politically feasible in a democracy and what economists see as efficient allocation of a scarce resource; kicking an old person out of their house is never going to fly, but economically speaking, kicking an old person out of their house (and paying them well for it) and moving them to a smaller apartment to allow a 40 year-old FAANG engineer with 2 kids to move in is an obvious net win.

What we have now is the exact opposite. If the old person were to move to a smaller residence, they cannot pay less in taxes due to Proposition 13[1], so will be paying the same or higher taxes for a smaller place.

There's tons of issues with this proposal, I don't think it's worth pursuing if for no other reason than it's completely infeasible to pass as a law. It will also effectively be a bit regressive (though only down to middle-class; the very poor are not directly affected by this; if anything the landlord is going to be able to pay slightly less taxes, since they will want to charge a much lower premium on moving than owner-residents). However I think you are mostly barking up the wrong tree with regards to your criticisms of it.

1: Yes there are some limited exceptions, but I don't think it's possible for your taxes to go down unless you move to a place that is worth less than the inflation (max 2%) adjusted value of what you purchased your house for. A retired person who has lived in their house for many years in SV, that translates to "move a long ways away to the middle of nowhere." if you want to pay less.