COST(Commonly Self-Assessed Tax) privatizes fiscal authority for an increased allocative and investment efficiency by introducing a personally-set tax on currently held assets: The current asset owner sets a price for it, which serves as the initial price in the “Texas shootout” style auction. The owner needs to pay a tax proportionate to the value which was set by him for the asset. The mechanisms of free markets now ensure a perfect allocative and investment efficiency: An artificially low price to avoid a high tax burden would make a loss of ownership on the asset likely. Conversely, a high value set for an asset to exclude it from the market is penalized with a high COST. Thus, the COST on assets equals the cost of holding assets when you are trying to keep them out of the market.

Proponents: Eric Posner, Glen Weyl

For further interest on this topic:

http://radicalmarkets.com/chapters/property-is-monopoly/