The original use of the word hypothecation was for a pledge of property as collateral for a debt without transfer of possession to the party making the loan. The opposite arrangement is common with modern mortgages - the bank retains legal ownership of the property until the debt is paid off.

A more recent use of the word is as a contraction of "hypothetical dedication", as in a "dedicated tax" to be collected for a specific purpose. For instance, in the United States the Gasoline Tax (a tax on sales of motor vehicle fuel) is dedicated to the funding of transportation infrastructure. Another example is a dedicated tax on the private trading of securities (for example, 0.3 cents per dollar traded) used to fund public infrastructure programs directly (such as the building of a water treatment plant) or to pay the finance costs of such programs.

Dedicated taxes are often subject to unexpected shortfalls and surpluses. This may create political pressure to adjust the tax, to budget non-dedicated revenues for the purpose in question, or to reallocate surplus funds to other purposes.

• See also: Security interest - hypothecation

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