Reduce Unnecessary Spending Act of 2010 - Amends the Impoundment Control Act of 1974 (ICA) to require the Office of Management and Budget (OMB) to transmit, within 45 days of a congressional session after the enactment of the funding in question, a message to Congress with specified information requesting any rescission the President proposes under the procedures in this Act.
Prescribes requirements for timing and packaging of rescission requests.
Authorizes OMB, subject to a specified time limit, to withhold funding from obligation temporarily if the President proposes a rescission.
Prohibits the President from invoking such expedited procedures or such authority to withhold funding on more than one occasion for any Act providing funding.
Sets forth procedures for expedited congressional consideration of proposed rescissions.
States that, if budget authority or funding is rescinded under the ICA, the amount so rescinded shall revert to the fund whence it came (general fund, trust fund, special fund, revolving fund, and so on as applicable), except to the extent legislation specifies otherwise.