mathbabe

Yesterday we had a tax expert come talk to us at the Alternative Banking group. We mostly focused on the mortgage tax deduction, whereby people don’t have to pay taxes on their mortgage. It’s the single biggest tax deduction in America for individuals.

At first blush, this doesn’t seem all that interesting, even if it’s strange. Whether people are benefitting directly from this, or through their rent being lower because their landlord benefits, it’s a fact of life for Americans. Whoopdedoo.

Generally speaking other countries don’t have a mortgage tax deduction, so we can judge whether it leads to overall more homeownership, which was presumably what it was intended for, and the data seems to suggest the answer there is no.

We can also imagine removing the mortgage tax deduction, and we quickly realize that such a move would seriously impair lots of people’s financial planning, so we’d have to do it very slowly if at all.

But before we imagine removing it, is it even a problem?

Well, yes, actually. Let’s think about it a little bit more, and for the sake of this discussion we will model the tax system very simply as progressive: the more income you collect yearly, the more taxes you pay. Also, there is a $1.1 million (or so) cap on the mortgage tax deduction, so it doesn’t apply to uber wealthy borrowers with huge houses. But for the rest of us it does apply.

OK now let’s think a little harder about what happens in the housing market when the government offers a tax deduction. Namely, the prices go up to compensate. It’s kind of like a rebate: this house is $100K with no deduction, but with a $20K deduction I can charge $120K for it.

But it’s a little more complicated than that, since people’s different income levels correspond to different deductions. So a lower middle class neighborhood’s houses will be inflated by less than an upper middle class neighborhood’s houses.

At first blush, this seems ok too: so richer people’s houses are inflated slightly more. It means it’s slightly harder for them to get in on the home ownership game, but it also means that, come time to sell, their house is worth more. For them, a $400K house is inflated not by 20% but by 35%, or whatever their tax bracket is.

So far so good? Now let’s add one more layer of complexity, namely that, actually, neighborhoods are not statically “upper middle class” or “lower middle class.” As a group neighborhoods, and their associated classes, represent a dynamical system, where certain kinds of neighborhoods expand or contract. Colloquially we refer to this as gentrification or going to hell, depending on which direction it is. Let’s explore the effect of the mortgage tax deduction on how that dynamical system operates.

Imagine a house which is exactly on the border between a middle class neighborhood and an upper-middle class neighborhood. If we imagine that it’s a middle class home, the price of it has only been inflated by a middle-class income tax bracket, so 20% for the sake of argument. But if we instead imagine it is in the upper-middle class neighborhood, it should really be inflated by 35%.

In other words, it’s under-priced from the perspective of the richer neighborhood. They will have an easier time affording it. The overall effect is that it is easier for someone from the richer neighborhood to snatch up that house, thereby extending their neighborhood a bit. Gentrification modeled.

Put it another way, the same house at the same price is more expensive for a poorer person because the mortgage tax deduction doesn’t affect everyone equally.

Another related point: if I’m a home builder, I will want to build homes with a maximal mark-up, a maximal inflation level. That will be for the richest people who haven’t actually exceeded the $1.1 million cap.

Conclusion: the mortgage tax deduction has an overall negative effect, encouraging gentrification, unfair competition, and too many homes for the wealthy. We should phase it out slowly, and also slowly lower the cap. At the very very least we should not let the cap rise, which will mean it effectively goes down over time as inflation does its thing.

If this has been tested or observed with data, please send me references.