"Total debt of the federal government can increase in two ways. First, debt increases when the government sells debt to the public to finance budget deficits and acquire the financial resources needed to meet its obligations. This increases debt held by the public. Second, debt increases when the federal government issues debt to certain government accounts, such as the Social Security, Medicare, and Transportation trust funds, in exchange for their reported surpluses. This increases debt held by government accounts. The sum of debt held by the public and debt held by government accounts is the total federal debt. Surpluses reduce debt held by the public, while deficits raise it. Total federal debt outstanding was $14,344 billion on June 29, 2011. The U.S. Treasury Secretary Timothy Geithner announced that the federal debt reached its statutory limit on May 16, 2011, and that he had declared a debt issuance suspension period, allowing certain extraordinary measures to extend Treasury's borrowing capacity until early August 2011. Since May 16, debt subject to limit has been held just below $14,294 billion. Funding federal operations could soon become complicated without a debt limit increase. […] On January 28, the Senate passed an amended version of H.J.Res. 45, which the House passed on February 4 and the President signed on February 12 (P.L. 111-139), raising the limit to $14,294 billion. This report will be updated as events warrant."
CRS Report for Congress, RL31967