Article I, Section 8 of the U.S. Constitution states, “The Congress shall have power to lay and collect taxes, duties, imposts, and excises, and to pay the debts and provide for the common defense and general welfare of the United States; but all duties, imposts and excises shall be uniform throughout the United States.”
In addition to the taxing powers in Article I, the 16th Amendment authorized Congress to establish a national income tax. The power to appropriate federal funds is known as the “power of the purse.” It gives Congress great authority over the executive branch, which must appeal to Congress for all of its funding.
The federal government borrows money by issuing bonds. This creates a national debt, which the United States is obligated to repay.
www.justicelearning.org, The United States Constitution, what it says, what it means, A Hip Pocket Guide (Oxford University Press)