Donald Trump is expected to release a tax plan in the next few weeks. What will it say?

It’s always risky to predict what Mr. Trump will do, but we can find some clues from his recent comments on taxes, which have spooked supply-side tax-cutting conservatives with their extensive hints about his unorthodox approach to tax policy.

First, the good news for anti-tax conservatives: He has identified three areas in which he wants to cut taxes.

1. Mr. Trump wants a middle-class tax cut. There are many different ways to do that (for example, so-called reform conservatives have called for a larger child tax credit to benefit middle-class families with children). But in other comments on taxes, Mr. Trump has emphasized the need to simplify the tax code by eliminating credits and deductions while lowering rates. So it’s likely Mr. Trump would structure his middle-class tax cut in the simplest way possible: by reducing the marginal tax rates that apply to moderate incomes.

2. He is also looking to cut taxes on some wealthy people. “I want to lower taxes for people that are making a lot of money that need incentives,” he said in a Bloomberg interview last Wednesday. That could mean a lot of different things — he may want to cut tax rates all the way to the top of the income spectrum, or he could simply be restating his desire to cut corporate income taxes, as discussed below.

3. He says he wants to lower corporate income taxes to encourage companies to invest here instead of lower-tax countries abroad.

As Mitt Romney reminded us, corporate taxes are ultimately borne by individuals. And while economists debate exactly how the cost of corporate tax is apportioned among workers and owners of capital, the consensus view, as reflected in estimates by the congressional Joint Committee on Taxation, is that owners of capital bear the greatest share — 75 percent, by the committee’s estimates. That is, a corporate tax cut is mostly a tax cut for the upper class, not for the middle class, though to the extent it encourages business investment and economic growth, it could have broadly shared positive economic effects.

Mr. Trump has also talked about the problem of so-called corporate inversions: when American companies relocate their headquarters abroad for better tax treatment. But unlike many Democrats, who want to find a way to prohibit inversions, he has focused on encouraging American companies to bring their overseas profits home with a tax break like a repatriation holiday, which allows them to do so while paying less American corporate income tax than would usually be required.

A repatriation holiday in 2004, though, had no apparent positive effect on domestic investment. Today, the rationale for a repatriation holiday is especially unclear because American firms already have extensive access to cheap capital for domestic investment because of low interest rates and accumulated domestic profits.

Then there are three kinds of tax increases Mr. Trump has floated.

4. He has said he would abolish various tax deductions and credits. This would be a part of his effort to simplify the tax code so he can, as he put it in August, “put H&R Block out of business, knock them out, put them out of business.”

Mr. Trump hasn’t said which deductions and credits he would eliminate, which isn’t unusual for a Republican candidate for president. Mr. Romney’s 2012 tax plan emphasized extensive-but-unspecified base broadening through the elimination of deductions and credits, and Jeb Bush said in May he would take a similar approach, in each case as a way to pay for reductions in tax rates.

It’s the other two ways Mr. Trump would raise taxes that set him apart from most Republicans.

5. He has called for higher tariffs on certain imports. In June, he called the North American Free Trade Agreement a “disaster.” He also said he would induce Ford to move an auto plant back to the United States by threatening a 35 percent import tax on cars produced in Mexico. The prime goal of such tariffs would be to discourage imports and encourage companies to produce domestically. But to the extent people continued to buy imported goods despite new tariffs, the government would collect new tariff revenue.

6. Mr. Trump has called for higher taxes on hedge fund managers and other people who earn “carried interest” income, and said it’s “outrageous” how little tax some very rich people pay. Carried interest is a kind of income that arises in investment funds that have limited partners (people who invest money) and general partners (people who manage the funds and provide expertise.) The general partners receive an equity stake in the fund in exchange for their work, and generally, the fund is set up to provide a very high rate of return on the general partners’ equity if the fund performs well.

Economically, that income is labor income, because the fund managers are receiving it in exchange for their work managing the fund. But because it is treated as investment income for tax law purposes, the managers enjoy the preferential tax rates typically associated with capital income, which can be about 20 points lower than tax rates on labor income.

Carried interest gets a lot of attention because the current policy of preferential taxation is hard to justify; even if (like many economists) you believe there are good reasons to tax capital income at a preferential rate, it’s hard to make the case that carried interest income is really capital income. But the fiscal impact of taxing carried interest income at ordinary income rates would be small: about $2 billion a year in added revenue within a nearly $4 trillion federal budget.

The key question is how broadly Mr. Trump is speaking when he says, as he did last Wednesday with Bloomberg, “I would let people that are making hundreds of millions of dollars a year pay some tax, because right now they’re paying very little tax and I think it’s outrageous.” If he is just talking about the (symbolically appealing but small) issue of carried interest, his tax hikes on the rich won’t go very far toward paying for middle-class tax cuts.

But if he really wants to collect significantly more taxes on people making hundreds of millions of dollars a year, he could propose raising tax rates on capital income, or greatly curtailing the availability of tax deductions to people with high incomes, or even raising tax rates on ordinary income at the top of the income spectrum.

Back in 2000, when he was flirting with a run on the Reform Party line, Mr. Trump proposed a 14.25 percent one-time wealth tax on people with high net worth in order to pay down the national debt. I don’t expect him to resurface that proposal — such a tax is probably unconstitutional, and the politics are different now, especially because he’s running as a Republican — but his past proposal suggests he does not have a strong, ideological aversion to significantly higher taxes on the rich.

Mr. Trump has also made two key statements about the structure of the tax code that are likely to shape what he proposes.

7. He has defended graduated taxes. In usual Donald Trump style, his statements about the flat tax have meandered into self-contradictory territory. Repeatedly in interviews, he has held out the flat tax as a possible long-run reform, though he says he prefers to start by simplifying the existing tax code. But last week on Fox & Friends, he offered a major concern about the flat tax:

The one problem I have with a flat tax is that rich people are paying the same as people that are making very little money, and I think that there should be graduation of some kind, because as you make a certain amount of money you should graduate upward.

Of course, lack of graduation is the defining feature of a flat tax; if you are in favor of graduated rates, you’re against a flat tax.

8. He has said he wants to reduce taxes over all. In 2012, Mr. Romney ran into trouble when discussing his tax plan because of his promise of revenue neutrality. The federal budget deficit was very large, and he promised his plan to reduce tax rates by 20 percent would not reduce government revenues over all. Unfortunately, the math of that promise proved impossible when combined with his promise not to raise taxes on any taxpayers making less than $200,000.

Mr. Trump is making no such bean-counterly promises. Even as he is open to raising taxes on some individuals, he is running on a net tax cut over all.

“We’re the most highly taxed nation in the world,” he said, incorrectly, on Fox News last week. “That’s why taxes have to come down.”

This promise of a tax cut fits with Mr. Trump’s more unconstrained view of fiscal policy. While other Republicans (and many Democrats) warn about the long-term fiscal gap, he insists that cuts in Social Security, Medicare and Medicaid are unnecessary. “I’m going to make us so rich you don’t have to do those things,” he said in April. Similarly, he dismisses the fiscal cost of a wall along the southern border. It might be expensive, but he will make Mexico pay for it, he says.

The supply-side branch of the Republican party may not be keen on Donald Trump’s tax rhetoric. But I strongly suspect he will imitate the supply siders in at least one way: He will say his tax plan will make us much richer, and therefore generate tax revenue that goes a long way to offset the revenue loss from cutting taxes.