Here's what the House Freedom Caucus's members have said they're looking for.
Members of the group generally endorse the same basic principles for reform: Reduce tax rates for everyone. Then, to make up for some of the revenue the government is foregoing under those new rates, eliminate special deductions, exemptions and loopholes that allow certain categories of taxpayers to avoid paying taxes on portions of their income.
This has long been the position of conservative Republicans, and it is also the approach embodied in the plans proposed by Republicans, including Trump and Ryan. For instance, the plan Ryan and his colleagues in the House put forward last year would eliminate all deductions for individual taxpayers — except for the deductions for mortgage interest and charitable giving. Those deductions allow Americans to avoid taxes on money they pay in interest on their homes, along with any donations they make.
That plan might not go far enough for a conservative lawmaker like Rep. Thomas Massie (R-Ky.). In 2013, Massie told Bloomberg he supported a single tax rate for all taxpayers, with no exceptions whatsoever. “I love the flat tax, and I’m not afraid of getting rid of every deduction,” Massie said.
All the same, mainstream Republicans are basically in agreement with their party's conservative faction when it comes to taxes — at least to a far greater degree than they were on health care.
You can read the rest at the Washington Post.