I am wrong about that in a Closed Access economy. And, this is one of many reasons why Closed Access is so damaging.
Here is a tweet from Kim-Mai Cutler, who does some great work on housing issues in California:
My first instinct is to naysay this tweet. But, that's because my instinct is an Open Access instinct. For classical economic models to work, we have to live in a sufficiently open system. In Phoenix, making real estate passthroughs more profitable would be an affordable housing policy, because it would induce new investment into rental properties, it would make the pre-tax return required by real estate investments lower, and it would lower the rent on properties of a given cost.Yep, let's make it even more profitable to operate real estate passthroughs while cutting affordable housing production during a housing crisis across most major American cities. (Exacerbating the status quo since the 1980s™.) https://t.co/gxY9ZwfdxW— Kim-Mai Cutler (@kimmaicutler) December 19, 2017
We can argue how many subsidies vs. taxes we should apply to real estate. Maybe we don't want to subsidize real estate. That would be fine. But, we should be able to agree that, in terms of rent - which is the important factor for actual housing affordability - subsidies to real estate investors will make the existing housing stock more affordable and will increase supply.
But, this doesn't happen in Closed Access cities. There is a political limit to supply in those cities. So, if tax policy shifts to give landlords more profit, they do pocket the profit. It doesn't matter if new capital would be drawn to real estate in a Closed Access city. Supply does not reflect economic costs and benefits.
To the extent that this benefits landlords while pulling back on mortgage interest deductions reduces benefits to homeowners, this set of policies probably does level the playing field a little more compared to how it has been in Closed Access cities, so that owner-occupiers with access to credit may be less likely to outbid landlords on existing units.
In general, Closed Access markets aren't governed by supply and demand, though. They are governed by the battle over economic rents that are the result of political exclusion. So, on new units, if the basic building cost would be $200,000 per unit, and they sell for $600,000 per unit, the difference will inevitably be claimed by various interest groups. Mostly, the difference will be claimed through various impositions, fees, and taxes, that are negotiated between local governments and the builders.
So, policies like tax subsidies don't affect supply. Instead, they affect prices - how far prices are above the natural market cost that would arise in a market that allowed new supply. And, to a certain extent, they reflect a battle between various levels of government about who gets to claim the economic rents from exclusion.
Now, workers who might earn $100,000 in Atlanta may move to San Francisco where they earn $150,000, but with $40,000 in additional costs. $20,000 of that might go to the landlord, $10,000 to the local government in taxes, and $10,000 to the federal government in taxes.
The proposed policy of eliminating the deductibility of local taxes might shift the economic rents, in the long run, all else equal, with $18,000 going to the landlord, $9,000 going to local government, and $13,000 going to the federal government. (These are broad, made up numbers to help think about the context.) So, reducing the SALT deduction is really a way for the federal government to get its hand on some of those economic rents.
It's tempting to say, let's find ways to tax those cities even more, until all the economic rents flow to Washington and there is no more advantage to political exclusion. But, the best solution would be to open those cities up so that more Americans can benefit from the amenities and characteristics that allow those cities to collect economic rents to begin with.
On the other hand, our chosen policies have been so poor that bringing down home prices through targeted taxes on Closed Access cities would be a huge improvement on the policies we chose to implement in our zeal to bring down home prices.
In any case, the core of the problem is Closed Access. Where the idea that capitalists just pocket public largesse might normally be fallacious, Closed Access makes it true. And, this reasonably leads to a plurality in public opinion to enforce policies that are explicitly damaging.