Worldbuilders often have settings in which tax policies are key drivers of conflict. This is as it should be, given that taxes often drive conflict in the real world, for very good reasons. But typically, the decisions that a fictional ruler face are boiled down to “Do I want money? If so, tax everything that moves.” In the real world, things are more complex. And introducing a bit of carefully chosen complexity into your stories can make the conflicts a lot more interesting.

Our current discussion is based on the seminal model of Margaret Levi. Based on a deep review of the history of governments, Levi starts from the assumption that in general, sovereigns want to maximize their tax revenue. (You can read a nice summary of the model here.) But this does not simply mean jacking taxes up as high as they can go.

First of all, the more you tax, the more opposition you get from those being taxed. This is obvious, but it has some notable consequences. A weaker regime will be able to tax less, because serious opposition could bring it down. Additionally, taxes will tend to fall more heavily on social groups that are less able to resist the government (often because they are poor!), or who depend on the government more, or who would benefit directly from the additional government projects that the tax revenues would fund and are thus more willing to bear the burden. In any event, the rulers will have to limit their taxation if they don’t want to antagonize the people.

Second, the higher the tax rate, the more that economic activity becomes depressed as many businesses simply become unprofitable. Moreover, it becomes worth it for people to rearrange their businesses to pay less tax, or even cheat on their taxes altogether. As a result, if you increase taxes by ten percent, say, your tax revenue will rise by somewhat less than ten percent. And at a certain point, tax collection actually goes down with higher taxes. (This concept is popularly known as the Laffer Curve.)

So a ruler will have to figure out the optimal tax policy for generating revenue. This is a difficult problem, especially if you don’t have a lot of data about the economy. Often, rulers get it wrong and set the tax rate too high for the amount of revenue they want to collect. (It is much less common to set the tax rate too low!)

This basic issue also functions across time periods; collecting lots of taxes this year will often mean that the economy’s growth will slow down in the future, reducing tax collection later. As a result, Levi notes that a major factor in the taxation decisions of sovereigns was their discount rate—that is, how willing they are to forego money today in exchange for more money tomorrow. 

(A quick example: suppose you have an opportunity to invest $100 today, and in a month you’ll get back $110 guaranteed. If you have money in the bank and won’t miss $100, you’ll happily invest the money for a good return. If you only have $100, on the other hand, and you need to spend it on food, it’s another matter entirely. Still, you might be willing to invest the hundred dollars if you would get back a thousand; for that much money, you’ll find some way to last the month. In the first case, you have a relatively low discount rate; you can afford to be patient. In the second case, you have a relatively high discount rate; you need money today, and it would take a massive amount of money in the future to get you to give up what you have.)

Levi notes that sovereigns facing a crisis—particularly a war—needed lots of money today, and were more willing to raise taxes for current revenue even if it harmed future growth, and even if it provoked domestic opposition (to a point). In other words, these rulers had a very high discount rate.

Next, certain types of taxes take different types of bureaucratic infrastructure; if you don’t have the infrastructure, you can’t levy the tax. For example, to tax incomes, you need a way to monitor how much money people make. This is tremendously hard, which is why direct income taxes across all of society were nearly unknown until the early 1900s. And some kinds of taxes would cost more to administer than you would actually raise!

A sovereign will then want to invest in new bureaucracy, to be able to collect more taxes in the future. But such investment takes money and time, and it usually provokes opposition from society—people resent intrusions into their privacy, and know that higher taxes are going to result in the future.

Levi’s model thus has a number of moving parts, including:

• the discount rate of the sovereign;
• the capability of the tax-collection apparatus;
• transaction costs for commerce, and for tax collection (which include information/monitoring costs, and fees, operating expenses, and other forms of friction); and
• the relative bargaining power of the state versus different classes in society.

Levi’s entire discussion includes many other complex facets, including the concept of quasi-voluntary compliance which I already touched upon in Beyond Kings and Princesses in the discussion of bureaucracy; I hope to write about more from Levi in future posts. But even this starting overview provides some useful tools for worldbuilders looking to juice up their political conflicts.

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(This post is part of Politics for Worldbuilders, an occasional series. Many of the previous posts in this series eventually became grist for my handbook for authors and game designers, Beyond Kings and Princesses: Governments for Worldbuilders. The topic of this post belongs in the planned second book in this series, working title Wealth [Commerce?] for Worldbuilders. No idea when it will be finished, but it should be fun!)