The Dual Role of Taxes

The most intuitive reason for taxes to exist is to help pay for common services and public goods that everyone uses. This is why many people love to tax the rich: it seems fair to ask the people who can afford it to pay more for the things that everyone uses.

However, not all taxes are created equal. A tax that is only designed to maximize revenue can have detrimental effects on the economy. For example: let's say that sales tax was increased to 50%. While on paper it may seem that revenue may increase by X%, in reality the amount of sales in the economy may decrease making the total amount of revenue lower after the tax is instated.

Now, let's say that our goal as a government is to reduce the amount of carbon emissions from cars on the road. We could apply a selective sales tax to gas, which would increase the price of gas and reduce the amount of gas that people buy. The direct effect of this would be that people would use less gas.

• For city dwellers, this could result in people using public transportation more often, since both personal and ride sharing would be more expensive.
• For rural/suburban commuters, this could result in either moving to cities (which reduces the amount of cars on the road) or using electric cars.
• For businesses which rely on gas to operate, e.g. tractors or delivery trucks, this could result in them switching to electric vehicles. This can hurt businesses in the short term, but the government can aid the transition via subsidies.

The point is that taxes can be used to influence behavior in addition to raising revenue. This is why it's important to understand the effects of a tax before implementing and/or voting for it.

How this applies to protocols

Protocols are a form of governance, and as such they can use taxes to influence user behavior. This is already implemented in many layer one blockchains:

• A tax on transactions to discourage spam. This already exists in the form of transaction fees.
• A tax on storage, to discourage state bloat. This exists in Solana in the form of rent, and on Ethereum in the form of storage/storage refunds.
• A tax on CPU resources, to encourage developers to optimize their code.

These also exist in the DeFi space:

• Automated market makers give fees to liquidity providers from traders crossing a protocol-defined spread between the bid and the ask, which is usually referred to as the "trade fee". For example, Uniswap V2 has a 0.3% spread on every pool.
  • 1/6 of this may be taken by the Uniswap protocol.
• Borrowers of borrow-lend markets pay interest to depositors, usually based on the utilization rate of the lending market.
  • A percentage of the spread goes to the DAO.

Understanding the effects of taxes is important for protocol designers, since they can be used to influence user behavior. For example, if a protocol wants to encourage users to use a specific token, it can give a tax rebate to users who use that token-- e.g., a stablecoin might buy a lot of governance power to make it cheaper to use their stablecoin.

Other Thoughts/Conclusion

I was inspired to write this post by a short YouTube video about Singapore's public transit system. They impose a very high tax on cars: a Honda Civic costs over $100k USD equivalent. This has resulted in a lot of people using public transit, which has reduced traffic and pollution and has increased the utilization/ROI of investing in the public transportation system.

Taxes are an age-old tool for governments to influence behavior. We may be able to rely on tested economics to help us design better systems for capturing value.