While amendments to a ways and means bill are subject to all the normal rules respecting legislation, there are additional restrictions resulting from the fact that the bill is based on a ways and means motion.
Amendments that exceed the scope of the ways and means motion on which the bill is based are procedurally unacceptable. A new ways and means motion is required prior to such an amendment being moved. Since the House must adopt any new ways and means motion, such an amendment cannot be moved in committee.
Amendments to decrease the amount of a tax or limit its incidence do not require a ways and means motion and are admissible both in committee and at report stage.
Any amendment exceeding the provisions of the authorizing ways and means motion on which the bill is based may be proposed and considered only at report stage. This can be done only if the House has adopted a second ways and means motion authorizing the terms of the amendment.