# Market share tax

Market share tax is a tax on a corporation's net income at a rate that depends on the largest market share that this corporation or its corporate group in total holds in any single industry, reaching a tax of up to 100% of net income at 100% of the group's market share.
The direct goal of this tax is to balance out the incentive that unregulated free markets create for corporations to create barriers to entry, become the dominant supplier, charge monopoly prices and earn a higher profit margin without the need to innovate or to produce superior goods.
A vast majority of corporations have no significant market share or influence over the market price or quality and so are not the target group of a market share tax. To avoid making tax accounting more complicated for these corporations, they can be exempt from the tax if their group's highest market share is low, for example below 2%. A lower bound can also be set on the group's annual revenue to exclude groups that only have a significant share in a small or nascent industry.
Market share tax as a policy was first proposed anonymously on January 29, 2013 on policyproposals.com for use in the USA and then independently by Robert Peetsalu on December 1, 2024 for use globally.

## Expected policy effects

Effects that such a tax is expected to have compared to a fixed corporate tax rate:
* A lasting reduction in the rate of transfer of wealth, thus reducing class conflict between workers and owners, between spenders and savers, increasing total spending and thus productivity and invigorating the economy.
* Likely higher amount of collected tax compared to a fixed rate corporate tax. This is due to corporations with a majority market share tending to have a significantly higher profit margin and having to pay a significantly higher proportion of their net profit as a market share tax.
* In order to increase their profitability, corporate groups that already hold a significant share in a market will avoid anti-competitive practices that would further increase their market share, like predatory pricing, mergers and acquisitions, anticompetitive agreements, exclusive deals and tie-in arrangements.
* In order to increase their profitability, corporate groups that already hold a majority share in a market will be incentivized to reverse their most recent mergers in that market or to spin off their niche products into separate corporations and sell them to competitors who have not yet reached a significant market share. This will in turn reduce the corporation's ability to engage in anti-competitive practices in the future.
* Currently monopolistic markets return to competitive prices and quality of supplied products and services.
* Stock prices of corporations that dominate their markets will deflate.
* Stock prices of smaller corporations will receive more attention from investors.
* Tax accounting and financial reporting will become more involved for groups with a market share above the lower bound.
* Existing monopolies are dissuaded from absorbing downstream markets through vertical integration.
* Private equity firms are dissuaded from buying up small competing businesses in the same region to drive up prices, as this would increase the market share of the consolidated corporation and increase its market share tax, reducing its expected profitability and by extension its stock price and the overall profitability of the buy-to-sell strategy.

## Tax evasion risks and preventive measures
### Online sales

A corporation with significant market share could try doing sales online without incorporating in the tax jurisdiction. To prevent this, corporations should be required to incorporate a subsidiary in the jurisdiction if it makes sales to customers located in that jurisdiction. There are some exceptions where jurisdictions have made agreements regarding taxing online sales, in essence uniting some of their markets.

### Profit shifting

A subsidiary doing the sales could try finding a legal way to transfer income or assets to a foreign parent or another subsidiary in its group or a seemingly unrelated corporation owned by the same shareholders without having to pay taxes on this income. To prevent this, all corporations should have to follow the arm's length principle when dealing with any other corporation and all such dealings have to be accounted for and available for auditing.

### Faking competition

Owners of a corporate group could create new seemingly competing corporations that would buy out parts of their business in order to reduce their group's market share while retaining the profits. To prevent this, a corporation's market share tax should be based on the total revenue made by all corporations in its group as well as all other corporations majority-owned by the same shareholders. Also, anti-trust laws should allow court rulings to declare that corporations have to pay tax on their combined market share even if they don't belong to the same ownership group in case there is evidence that they have artificially separated their ownership groups through intermediaries to evade the tax.

### Moving to a wider industry category

A corporation could try to lobby for its categorization under a different industry that has more competition and a smaller resulting market share or for switching to a wider, more abstract industry classification in general to include more products and services that are not in direct competition. To prevent this, an internationally accepted and detailed industry classification should be used and anti-corruption laws should be set in place.