Tax experts and lawyers for both online and brick-and-mortar retailers on Wednesday urged Congress to pass Internet sales tax legislation—but they couldn’t agree on what the bill should look like.

Testifying before the House Judiciary Committee, representatives of an electronic-commerce group, shopping malls and other organizations offered different proposals that would aim to make it easier for states to collect taxes from online retailers. Only one of them, however, identified the Senate’s Marketplace Fairness Act as a viable solution.