Fine Grain Futarchy Zoning Via Harberger Taxes

“Futarchy” is my proposed system of governance which approves a policy change when conditional prediction markets give a higher expected outcome, conditional on that change. In a city setting, one might be tempted to use a futarchy where the promoted outcome is the total property value of all land in and near that city. After all, if people don’t like being in this city, and are free to move elsewhere, city land won’t be worth much; the more attractive a city is as a place to be, the more its property will be worth.

Yes, we have problems measuring property values. Property is only traded infrequently, sale prices show a marginal not a total value, much land is never offered for sale, sales prices are often obscured by non-cash terms of trade, and regulations and taxes change sales and use. (E.g., rent control.) In addition, we expect at least some trading noise in the prices of any financial market. As a result, simple futarchy isn’t much help for decisions whose expected consequences for outcomes are smaller than its price noise level. And yes, there are other things one might care about beside property values. But given how badly city governance often actually goes, we could do a lot worse than to just consistently choose policies that maximize a reasonable estimate of city property value. The more precise such property estimates can be, the more effective such a futarchy could be.

Zoning (and other policy that limits land use) is an area of city policy that seems especially well suited to a futarchy based on total property value. After all, the main reason people say that we need zoning is because using some land in some ways decreases how much people are willing to pay to use other land. For example, people might not want to live next to a bar, liquor store, or sex toy store, are so are willing to pay less to buy (or rent) next to such a place. So choosing zoning rules to maximize total property value seems especially promising.

I’ve also written before favorably on Harberger taxes (which I once called “stability rents”). In this system, owners of land (and property tied to that land) must set and may continuously adjust a declared property “value”; they are taxed per unit time as a percentage of momentary value, and must always agree to sell their property at their currently declared value. This system has great advantages in inducing property to be held by those who can gain the most value from it, including via greatly lowering the transaction costs of putting together big property packages. With this system, there’s no more need for eminent domain.

I’ve just noticed a big synergy between futarchy for zoning and Harberger taxes. The reason is that such taxes allow the creation of prices which support a much finer grain accounting of the net value of specific zoning changes. Let me explain.

First, Harberger taxes create a continuous declared value on each property all the time, not just a few infrequent sales prices. This creates a lot more useful data. Second, these declared values better approximate the value that people place on property; the higher an actual value, the higher an owner will declare his or her taxable value to be, to avoid the risk of someone taking it away. Third, these declared values are all relative to a standard terms of trade, not the varying terms of actual sales today. Thus the sum total of all declared property values can be a decent estimate of total city property value. Fourth, it is possible to generalize the Harberger tax system to create zoning-conditional property ownership and prices.

That is, relative to current zoning rules, one can define a particular alternative zoning scenario, wherein the zoning (or other property use limit) policies have changed. Such as changing the zoning of a particular area from residential to commercial on a particular date. Given such a defined scenario, one can create conditional ownership; I own this property if (and when) this zoning change is made, but not otherwise. The usual ownership then becomes conditional on no zoning changes soon.

With conditional ownership, conditional owners can make conditional offers to sell. That is, you can buy my property under this condition if you pay this declared amount of conditional cash. For example, I might offer to make a conditional sale of my property for $100,000, and you might agree to that sale, but this sale only happens if a particular zoning change is approved.

The whole Harberger tax system can be generalized to support such conditional trading and prices. In the simple system, each property has a declared value set by its owner, and anyone can pay that amount at any time to become the new owner. In the generalized system, each property has a declared value for each (combination of) approved alternative zoning scenario. By default, alternative declared values are equal to the ordinary no-zoning-change declared value, but property owners can set them differently if they want, to be either higher or lower. Anyone can make a scenario-conditional purchase of a property from its current (conditional) owner at its scenario-conditional declared value. To buy a property for sure, buy it conditional on all scenarios.

(For concreteness, assume that only one zoning change proposal is allowed per day per city region, that a decision is made on that proposal in that day, and that the proposal for each day is chosen via open public auction a month before. The auction fee can subsidize markets in bets on if this proposal will be approved and markets in tax-revenue asset conditional differences (explained below). A week before the decision day of a proposal, each right in a property is split into two conditional rights, one conditional on this change and one on not-this-change. At that point, owner declared values conditional on this change (or not) become active sale prices. Taxes are paid in conditional cash. Physical control of a property only transfers to conditional owners if and when a zoning scenario is actually approved.)

Having declared values for all properties under all scenarios gives us even more data with which to estimate total city property value, and in particular helps with estimating the difference in total city property value due to a zoning change. To a first approximation, we can just add up all the zoning-change-conditional declared values, and compare that sum to the sum from the no-change declared values. If the former sum is consistently and clearly higher than the latter sum over the proposal’s decision day, that seems a good argument for adopting this zoning proposal. (It seems safer to choose the higher value option with a chance increasing in value difference, and this all works even when other factors influence a decision.) At least if the news that this zoning proposal seems likely be approved gets spread wide and fast enough for owners to express their conditional declared values. (The bet markets on which properties will be effected helps to notify owners.)

Actually, to calculate the net property value difference that a zoning change makes, we need only sum over the properties that actually have a conditional declared value different from its no-change declared value. For small local zoning changes, this might only be a small number of properties within a short distance of the main changes. As a result, this system seems capable of giving useful advice on very small and local zoning changes, in dramatic contrast to a futarchy based on prices estimating total city property values. For example, it might even be able to say if a particular liquor store should be allowed at a particular location, or if the number of required parking spots at a particular shopping mall can be reduced. As promised, this new system offers much finer grain accounting of the net value of specific zoning changes.

Note that in this system as described, losers are not compensated by winners for zoning rule changes, even though we can roughly identify winners and losers. I’ve thought a bit about ways to add a extra process by which winners compensate losers, but haven’t been able to make that work. So the best I can think of is to have the system look at the distribution of wins and losses, and reject proposed changes where there are too many big losers relative to winners. That would force a search for variations which spread out the pain more evenly.

We are close to a workable proposal, but not quite there yet. This is because we face the problem of owners temporarily inflating their declared values conditional on a zoning change that they seek to promote. This might tip the balance to get a change approved, and then after approval such owners could cut their declared values back down to something reasonable, and only pay a small extra tax for that small decision period. Harberger taxes impose a stronger penalty for declaring overly-low values than overly-high values.

A solution to this problem is to use, instead of declared values, prices for the purely financial assets that represent claims on all future tax revenue from the Harberger tax on a particular property. That is, each property will pay a tax over time, we could divert that revenue into a particular account, and an asset holder could own the right to spend a fraction of the funds in that account. Such tax-revenue assets could be bought and sold in financial markets, and could also be made conditional on particular zoning scenarios. As such assets are easy to create and duplicate, the usual speculation pressures should make it hard to manipulate these prices much in any direction.

A plan to temporarily inflate the declared value of a property shouldn’t do much to the market price for a claim to part of all future tax revenue from that property. So instead of summing over conditional differences in declared-values to see if a zoning change is good, it is probably better to sum over conditional differences in tax revenue assets. Subsidized continuous market makers can give exact if noisy prices for all such differences, and for most property-scenario pairs this difference will be exactly zero.

So that’s the plan for using futarchy and Harberger taxes to pick zoning (and other land use limit policy) changes. Instead of just one declared value per property, we allow owners to specify declared values conditional on each approved zoning change (or not) scenario, and allow conditional purchases as well. By default, conditional values equal no-change values. We should tend more to adopt zoning proposals when, during its decision day, when the sum of its (tax-revenue-asset) conditional differences clearly and consistently exceeds zero.

Thanks to Alex Tabarrok & Keller Scholl for their feedback.

Added 11pm: One complaint people have about a Harberger tax is that owners would feel stressed to know that their property could be taken at any time. Here’s a simple fix. When someone takes your property at your declared value, you can pay 1% of their new declared value to get it back, if you do so quickly. But then you’d better raise your declared value or someone else could do the same thing the next day or week. You pay 1% for a fair warning that your value is too low. Under this system, people only lose their property when someone else actually values it more highly, even after considering the transaction costs of switching property.

Added 2Feb: I edited this post a bit. Note that with severe enough property limits, negative declared property values can make sense. For example, if a property must be maintained so as to serve as a public park, the only people willing to become owners are those who get paid when they take the property, and then get paid per unit time for remanning owners. In this way, city services can be defined and provided via this same decision mechanism.

Added 11July: On reflection, there’s not much need for the special 1% grab-back rule I proposed above. While it might be good rhetoric to allay fears, it isn’t actually needed. In principle it could reduce your loss from setting too low a price, but in practice I don’t think it will be possible to underprice that much; speculators will buy underpriced assets intending to sell them back.

Assuming that there’s a standard delay in transferring property, the moment someone grabs your declared value price, they must declare a new value. So you are either willing to grab it back at that price, and then set a new higher value, or you accept that they have a higher value for the property and can keep it. If you grab it back and set a higher value, they can of course take it at that new value; you can in effect go back and forth in an auction to see who values it more. Each time they grab from you will regret not having set a higher value; so this won’t go many rounds and will be settled quickly.

Added 21Oct2021: It has been pointed out to me that allowing owners to pay 1% of property value to get it back is at odds with allowing people to buy up big blocks all at once. Right after a big block is purchased, parts of that block could dramatically raise their prices, as a way to threaten to destroy the block. So I think this ability to pay 1% to get your property back should not apply when many properties are purchased at once as part of a block.