The Ways and Means Committee in the U.S. House of Representatives is its most powerful committee, because it controls the tax writing. This committee has authority over "a portfolio spanning including taxes, trade, Social Security and some Medicare spending."[1]
Article 1, Section 7 of the United States Constitution says: "All Bills for raising Revenue shall originate in the House of Representatives." Ways and Means is the committee traditionally tasked with originating taxation, or revenue bills. The analogous committee in the U.S. Senate is the Senate Finance Committee.