Legally Binding Budget Act of 2013 - Amends the Congressional Budget Act of 1974 (CBA) to require joint budget resolutions signed by the President instead of the concurrent resolutions now required (which do not have to be signed by the President). Revises accordingly the congressional procedures for considering joint budget resolutions.
Prohibits the consideration of budget-related legislation before the joint budget resolution becomes law.
Requires the joint budget resolution to set forth appropriate levels for the fiscal year beginning on October 1 of such year and for at least each of the four ensuing fiscal years for the public debt limit for display purposes only.
Permits revisions of joint budget resolutions already enacted.
Makes a conforming amendment to the Congressional Budget and Impoundment Control Act of 1974.
Makes it out of order in both chambers to consider any joint budget resolution, amendment, or conference report that contains certain matter prohibited by the CBA, particularly inclusion in the surplus or deficit totals of any outlays and revenue totals of the Old Age, Survivors, and Disability Insurance (OASDI) program under title II of the Social Security Act.
Considers the joint budget resolution as enforceable upon enactment or 15 days following presentment to the President, whichever occurs earlier. (Thus creates an automatic standing order upon a presidential veto of a joint budget resolution.)
Makes conforming amendments to: (1) the Rules of the House of Representatives, and (2) the Balanced Budget and Emergency Deficit Control Act of 1985 (Gramm-Rudman-Hollings Act).