National Activity Based Total Accountability Act of 2013 - Requires each state government that receives federal financial assistance in a federal fiscal year to submit a state fiscal accounting report for such fiscal year to the Director of the Office of Management and Budget (OMB) that includes: (1) a one-page summary listing the total funding and expenditures of each budget entity of the state government; and (2) a unit-cost summary for each such entity that includes a statement of funds available, a line-item listing for each agency activity that the entity began, attempted, continued, or completed, and a reconciliation of funds available with adjusted expenditures. Sets forth formulae for determining unit-cost and adjusted expenditures.

Requires the Director to: (1) publish each report on an OMB website, (2) ensure that such state reports use a standardized form that permits the comparison of information, (3) establish a uniform system for classifying programs and activities, (4) identify conduct for each agency activity that constitutes a completed instance of such activity, and (5) identify performance measures for each agency activity.

Requires the Director to inform each federal agency if a state fails to file such report and requires the agency to withhold 10% of any federal financial assistance provided to such state for the next fiscal year.