Decennial Census Accuracy Improvement Act of 1990

Decennial Census Accuracy Improvement Act of 1990 - Amends Federal census law to require the Secretary of Commerce to determine whether the tabulations of population of the respective States should be adjusted in order to correct for any under- or over-counting.

Provides that the tabulation for a State shall not be complete unless: (1) the Secretary determines that no adjustment is required in the tabulation of population for any State; or (2) appropriate adjustments for each State have been made, if it is determined that adjustment would improve the accuracy of census counts.

Requires that any incomplete tabulation reported to a State to be identified as preliminary and subject to adjustment.

States that if the deadline cannot be met to complete and report such data to the respective States the Secretary shall: (1) provide advance written notice to the Congress (including a statement of reasons and the anticipated compliance date); and (2) have until the second July 15th after the decennial census date to complete and report the tabulation of population to the respective States. Applies this Act to data obtained from the 1990 decennial census or any to follow.

Deems as a reference to such tabulation in its completed form as determined by this Act any requirement under Federal law that a tabulation of population for a State (as obtained in the 1990 or a later decennial census) be used.

Requires the Secretary to report on the data obtained from the 1990 decennial census to the appropriate congressional committees.

Declares that the authority to use the "sampling" statistical method shall be governed by this Act.