It is said that in life, two things are certain: death and taxes.

But there's a third certainty: Regardless of what happens to the first two, Washington's accountants and attorneys will find a way to prosper.

One might believe that the prospect of a simplified tax code that eliminates many deductions, exemptions and tax-shelter prospects would have Washington's tax attorneys, accountants, tax preparers, tax shelter writers, tax newsletters and financial planners up in arms.

But many said either that they don't believe the U.S. tax code will be simplified by the Department of Treasury's recent tax proposal or that -- if it is -- clients still will come to them for help.

"Any transition period" between the old and new tax systems "will generate a lot of business," said Christine Vaughn, a tax attorney for the Washington law firm of Vinson & Elkins. "Even after the dust clears, there will still be a lot of questions." Vaughn formerly worked for the assistant secretary for tax policy at the Treasury Department.

Financial planners conceded that adoption of the Treasury plan would eliminate some of their work in finding tax shelters. But elimination of many of the incentives for tax shelters and lowering marginal tax rates also will give investors more money -- which they will need help investing in more economically efficient projects.

The Treasury Department tax simplification proposal would eliminate an array of deductions and exemptions that help make tax preparation difficult. Treasury also proposes to eliminate 16 tax forms. By 1990, the Internal Revenue Service hopes to be able to prepare the tax returns for two-thirds of individual taxpayers, partly because the system would be so simple.

"I don't see any way that a proposal of this magnitude could do anything but help tax lawyers," said Cliff Massa, another Washington tax attorney and lobbyist. Along with the certainty that there will always be taxes comes the assurance that taxpayers will always have questions about them.

Even H & R Block, whose major business is preparing individual and corporate tax returns, says it doesn't expect a simpler tax system to affect business at its 340 locations in the Washington area or elsewhere.

If the Treasury proposal is passed, there will still be state and city tax forms to fill out and itemized deductions remaining for tax preparers to do, said a spokesman for the giant tax preparation firm.

The Treasury proposal would retain existing itemized deductions above certain levels for medical expenses and for casualty losses. But it would end the deduction for charitable contributions that amount to less than 2 percent of adjusted gross income, and eliminate deductions for state and local taxes.

In addition, the Treasury proposal would end deductions for business entertainment and limit per-person deductions for business meals to $10 for breakfast, $15 for lunch and $25 for dinner, including taxes and tips. Other provisions of the Treasury plan would make taxable the future issuance of "private purpose" tax-exempt bonds, which have been used by investers as tax shelters.

"The Treasury proposal repeals or consolidates about 65 provisions in the tax code," the Treasury Department said.

The proposals would reduce the number of individual taxpayers who itemize deductions from 36 percent to fewer than 25 percent, Treasury said. That means approximately two-thirds of those who now itemize would continue to do so.

The biggest blows to the tax shelter business would be proposals to lower tax rates; to tax real capital gains as ordinary income; to eliminate the accelerated depreciation system and replace it with something closer to true economic depreciation; to index net interest expense, generally limiting to $5,000 the amount of interest expense that can be deducted, and to treat some large partnerships as corporations for tax purposes.

"Yet opportunities for tax shelters will remain and several proposals are being made to further reduce these opportunities," the Treasury said.

Lower tax rates make the value of remaining deductions worth less, and eliminating preferential treatment of capital gains taxes could also reduce the incentive for some taxpayers to invest in certain tax shelter schemes, tax experts said.

The elimination of accelerated depreciation and the investment tax credit would remove the incentive for tax-avoiding taxpayers to invest in equipment or other goods that provide fast write-offs but are not necessarily economically efficient, Treasury has said. "This feature has been an important contributing factor to both the stockpiling of unused tax deductions and credits by some firms and the recent dramatic growth of tax shelters," Treasury said.

Indexing of net interest expense and limiting the amount of interest expense that can be deducted would make the value of that deduction less than under the current system.

However, one of the biggest blows to the tax shelter business may be the elimination of preferential tax treatment for some large partnerships and proposed restriction of their size.

The main tax advantage of these partnerships is that gains, losses and tax credits go to the partners rather than being taxed to the corporate entity. Corporations, particularly if their taxable income is negative or very low, might not benefit fully from tax credits or deductions for recovery of capital costs and interest expense. But partnerships can pass net operating losses along to the affluent partners who can use the losses to shelter other income.

The Treasury Department estimates that partnership losses may shelter as much as $35 billion of all individual income from taxation. About $28.6 billion in those partnership losses were reported by taxpayers with gross incomes before losses of at least $100,000, Treasury said. About 60 percent of the total was reported by taxpayers with incomes exceeding $250,000.

Finalco Group Inc., one of a handful of Washington-area firms that put together tax shelters, already has begun shifting its emphasis away from tax shelters and toward equipment leasing that would provide a return for investors, but no tax breaks.

"About a year-and-a-half ago, Finalco anticipated there might be some problem in the tax shelter business," said Finalco Chairman Terry Billingsley. "We're becoming a classic operating-lease company that's nontax-motivated."

McLean-based Finalco hasn't yet let go of its tax shelter business, which also involves leasing equipment to businesses. Many people seeking to avoid taxes invest in equipment leasing because they can get the tax benefits from the investment tax credit and accelerated depreciation.

Under the tax shelter, the investor puts up part of the cost of the equipment and borrows the rest. The investor then gets to write off the interest from the loan plus use the tax credits. Another party leases the equipment to a company that either cannot use the tax credits or, for economic reasons, just doesn't want to buy it.

Under one of Finalco's new programs, the investor would get a return by leasing the equipment for short periods of time only, and then leasing it again and again, Billingsley said. This program, the Finalco Income Fund, has been operating for about a year, he said.

In real estate shelters, taxpayers can defer payment of taxes by purchasing property and using accelerated depreciation rules to gain deductions exceeding the true economic depreciation in the early years of the investment.

Although the Treasury plan would attempt to get rid of tax shelters, Paul Finfer, president of Finalco, said that, in some areas, shelter planners can get around new laws proposed in the tax reform plan. "We have to be more creative and imaginative," Finfer said.

Financial planners said there would still be a need for their services in a simplified tax world because people would become less concerned with dodging taxes and more interested in investing in projects that would earn a good return.

Bethesda financial planner Susan B. Fulton said that the Treasury tax plan "won't affect the need for people to strategize." A large number of taxpayers might find the new "simplified" system more complicated than ever. In addition, financial planning will continue for retired people and those who usually seek advice when their financial situation changes, such as divorced taxpayers, retirees, heirs and highly paid professionals.

David S. Dondero, a financial planner in Alexandria, said with the lower tax rates, his clients' cash flow should improve and they will need advice on how to invest it.

For example, many taxpayers wanted to invest in oil and gas tax shelters, which provided a lot of tax breaks. Now the Treasury is proposing to eliminate virtually all of them. Many investors never got a decent return on their investment, but got a tax write-off anyway, Dondero said.

"People looking for good business decisions, that's what investing should be about anyway," Dondero said.

Clark Lee, a certified public accountant in Maryland, said that most of his clientele consists of small businesses that would continue to need him to prepare financial statements and give tax advice. "My clients don't really come to me to have tax returns done," Lee said.

Echoing Dondero's remarks, Lee said, "Sometimes people get obsessed with taxes and not the economic benefit."

And what about other tax advisers? Shortly after the Treasury plan was announced, the stock of Commerce Clearing House, a major newsletter that advises clients on taxes, rose strongly. The philosopy at the newsletter is that there will always be tax changes, and always something complex about taxes that will need to be explained.

"I see no problem," said James McNelis, a company vice president. "I don't think they're going to simplify it anyway. I have great faith in Congress and the lobbyists" to stop any tax-reform effort.