As anticipated, the Joint Statement on Tax Reform – the document released by the Big 6 tax negotiators, Treasury Secretary Steven Mnuchin, National Economic Council Director Gary Cohn, Senators Mitch McConnell and Finance Committee Chairman Orrin Hatch, House Speaker Paul Ryan and Ways and Means Committee Chairman Kevin Brady – while more detailed than the document the White House released in the spring, remains short on many key details.

It leaves it to Congress to turn these broad principles into comprehensive tax reform.

The release of this document begins an intensive effort on tax reform, currently the highest domestic priority for the President and Congress.

What follows is a review of some of the main points in the document highlighting where it has notable gaps and grey areas:

Corporate rate: The framework calls for a corporate rate of 20 percent and the elimination of the corporate alternative minimum tax. Because tax reform is expected to be incorporated in a budget reconciliation bill, which will require offsets for the rate reductions, it is expected that a great many tax expenditures (business credits and other special provisions) will be eliminated. However, excepting the preservation of credits for research and low income housing, the document otherwise remains silent as to which other provisions will be eliminated (the framework does suggest that some may be retained "as budgetary limitations allow"). The framework contemplates a pass-thru rate of 25 percent with anti-abuse mechanisms. The rate is probably aspirational; there have been indications that the tax writers believe budgetary constraints could push the rate up closer to 25 percent (and the rate reduction is likely to be phased in over several years, also for budgetary reasons).

Corporate tax integration: The framework suggest that the tax writing committees may consider "methods to reduce the double taxation of corporate dividends," a reference to Chairman Hatch's efforts to gain support for tax integration. In recent days Hatch has said that the rate reductions could be combined with integration. This language suggests that the Big 6 may not be fully united on the new structure of the corporate income tax; Chairman Hatch has said within the past week that the framework is "advisory" and the Senate Finance Committee will write its own reform plan in any event.

Interest expense: The framework provides that "the deduction for net interest expense …will be partially limited." This suggests that the Big 6 decided against total elimination but there is no guidance as what a partial elimination will entail.

Expensing: The framework calls for the immediate write-off of new investments "for at least five years", but will leave it to the Committees to fill in details as to what will be included and ultimately budgetary considerations will dictate the duration of any full expensing provision that is adopted.

International reform: There are some significant areas to be filled in with respect to the framework's discussion of international tax reform. The framework provides for a 100 percent exemption for dividends received from foreign subsidiaries by a US parent owning at least 10 percent of the foreign entity, and will deem as repatriated foreign accumulated profits prior to the new system going into effect. Although the framework states that foreign earnings held in illiquid, or "bricks and mortar" form will be taxed at a lower rate than liquid, cash assets it does not specify the rates, and further states that the deemed repatriation tax may be payable over several years. Moreover, prior tax reform proposals have suggested liquid versus illiquid assets be taxed at rates of 8.75 and 3.75 percent respectively, while prior formulations, including the proposal made by the Trump campaign, concerning length of time the value of those rates would be made payable have called for a ten year payout.

The framework proposes very generalized mention of provisions to address base erosion ("rules to protect the US tax base by taxing at a reduced rate and on a global basis the foreign profits of US multinational corporations"), but does not go any further in contemplation of details such as a specific rate or the mechanics of how this minimum tax will be applied (the House Freedom Caucus has indicated that they will vocally oppose a global minimum tax, while this issue has also been the source of growing discomfort amongst House Ways and Means Republicans as well in the setting of a precedent of this nature that could be increased at any point in the future, depending upon the political makeup across Congress and future Administrations). The framework also states that "the committees will incorporate rules to level the playing field between US headquartered parent companies and foreign-headquartered companies."

Individual taxation: The framework calls for three brackets, but suggests "an additional top rate may apply to the highest-income taxpayers" to insure progressivity in the system, and calls for doubling the standard deduction while eliminating the individual AMT and unspecified tax benefits (to offset the cost of lowering the rates). The framework also calls for enhanced credits to support care for children and non-child dependents, doubles the standard deductions, and states that "the committees will work on additional measures to meaningfully reduce the tax burden on the middle class," but does not provide any further detail as to what those measures will contain.

Death taxes: The framework contemplates the elimination of the estate and generation skipping taxes.

Other areas: Although the intent remains to enact comprehensive reform, the framework does not address and therefore leaves to the tax writing committees decisions relating to the treatment of currently tax-exempt entities, as well as tax treatment of retirement savings. However, there are indications that the tax writing committee staffs are reviewing the 2014 Camp comprehensive tax reform proposal for guidance on how to address these issues alongside many other areas at issue that also were not directly addressed in the most recent framework released.

For months now, the Big 6 have been saying that they are in agreement on 80 percent of tax reform, and the framework released today suggests that the 80 percent represents the easier issues: rate reduction, tax code simplification and the provision of tax relief for small business. The framework is silent, however, with respect to the tougher issues that have been instigating major divisions within both the Administration and the Congress. More specifically, the issues of primary concern include how to pay for rate reductions in order to comply with the budgetary rules that govern the reconciliation process; precisely how the current earnings and profits of US Company foreign subsidiaries will be taxed; and the rules that will apply to major areas of tax policy that will need to be addressed if they are to ensure this tax reform effort is ultimately comprehensive.

These issues are going to be left to the tax writing committees over the coming months; notably, the framework states its recognition that there are "special tax regimes that govern the tax treatment of certain industries and sectors", and these will need to be addressed and modernized.

In the final analysis, however, the resolution of whether tax reform will have a positive impact for any particular business or sector will depend on how these issues are resolved, and whether Congress will ultimately be successful in achieving the lower rate targets that the framework contemplates.