Natural Gas Market Adjustment Act of 1983

Natural Gas Market Adjustment Act of 1983 - Amends the Natural Gas Policy Act of 1978 to permit a purchaser to reduce the required take under a take-or-pay contract clause to 50 percent for the three-year period following enactment of this Act. Requires 30 days notice from a purchaser to a seller in any case where the purchaser makes the election.

Declares against public policy and unenforceable indefinite price escalator clauses. Defines such a clause as any contract provision which sets the price of natural gas by reference to prices for other commodities.

Prohibits the Federal Energy Regulatory Commission from denying a cost passthrough to an interstate pipeline under a contract entered into or renegotiated after enactment on the grounds that the amounts paid were excessive due to fraud or abuse, if such amounts are prudent purchases. Defines "prudent purchases" to include amounts paid for natural gas which bear a reasonable relationship to the fair market value of the gas. Sets forth guidelines for determining fair market value.