For year-end tax planning, cast an eye to a bigger bite next year

''Tax reform,'' they call it. Or maybe ''revenue enhancement.'' Whatever the euphemism (anything but a tax increase), many people are very likely to be sending more money to the Internal Revenue Service at the end of the 1985 tax year than at the end of this one.

Year-end tax planning in 1984 carries an additional twist of figuring out how to get your financial house in order, so it won't be battered by the high winds of what could be a more powerful Hurricane Sam - as in Uncle.

''We are advising clients that we feel certain there will be a tax increase next year,'' says Mario Borini, national tax director at Seidman & Seidman, an accounting firm.

''I don't see an overall tax rate increase,'' says Paul Anglin, a partner in the tax department at the Deloitte Haskins & Sells accounting firm. ''But I do think there will be a continuing broadening of the tax base, a limitation on deductions to bring in things that are not taxed now.'' Mr. Anglin is also head of Deloitte's personal financial planning department, and he, like some other tax experts, thinks 1985 will be a year of ''tinkering'' with the tax laws rather than widespread reform.

''If it's anything major, it probably won't happen in '85,'' agrees Robert Hanson, national director of tax practice at Arthur Young & Co., another firm. ''The debate is probably controversial enough that it will need more than a year to pass.''

Whatever changes do occur next year, these tax experts agree, they are more likely to affect families earning $50,000 and more in taxable income. Congress and the Reagan administration will find it politically easier to enlist money from this group in the war against the deficit.

There are, however, a few items of current discussion that could have some effect on middle-income people. For instance, there is the possibility of an elimination of non-mortgage interest payments as a deduction. This would cover auto loans, personal loans, credit card accounts, and perhaps even second homes.

For most other people, one rule of recent years is reversed: ''Generally, I would suggest accelerating income into '84 and postponing deductions into '85,'' Mr. Borini at Seidman & Seidman says. Because the tax bite on income is apt to be smaller this year than next, more deductions ''would do the taxpayer more good in a higher tax year,'' he said.

There are, however, some deductions that should be taken this year, if the expected tax reform scenario is played out. For instance, if the deductions for state and local taxes are going to be eliminated or reduced, as some people think, taxpayers should make any advance payments they can afford and the local government will allow this year.

''If you're considering a sale, look into closing before Dec. 31,'' Mr. Anglin says. ''We know what the tax rate on that sale is this year, but we're not sure about next year.'' The tax on long-term capital gains, for instance, could go from 20 to 25 percent. That would not be unprecedented, he points out: It stood at 25 percent for more than 70 years, until it was cut in the mid-'70s.

Not everyone is subject to the full 20 percent tax, he adds, just as they would not be subject to all of a 25 percent tax. It depends on your tax bracket and other deductions, so before unloading any stock or other property where this tax would apply, check with your tax accountant or tax attorney. Your broker may also be able to offer some insights as to whether a particular stock might appreciate enough to offset a higher tax. In most cases, it probably won't.

''I'm going to have to earn at least 10 percent more on that sale to be further ahead by waiting,'' Anglin notes.

The possibility of new tax legislation could also affect when people sell their homes, and when they buy them. If you're selling, says Borini, you may be better off doing it this year if taxes are a consideration. On the other hand, if you're planning to buy a home, you might wait until next year, because prices could be lower.

People seeking protection in traditional tax shelters can expect them to provide less coverage - with or without a new tax law. ''Eventually, we'll see the demise of most shelters,'' because of current law and a tougher IRS, Borini believes. ''Real estate and oil and gas will stay, but a lot of others will be cut off.'' High write-offs, where people could deduct three or four times their investment in the first year, will soon be a thing of the past, he adds. Also, registration - all public and private shelters and limited partnerships have to register with the IRS - will put a severe crimp in the shelter business.

This is also the time of year when many companies give year-end bonuses. In the past few years, tax experts have advised companies to hold off giving out bonuses until January, because progressive declines in the tax rate made it less of a burden to employees. Not so this year. With taxes more likely to be higher next year, any bonuses, including taxable gifts, should be passed out before New Year's, to give employees something more to celebrate: a smaller nibble from the taxman.

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