Before the end of 1988 gets much closer, financial advisers say, it's a good idea to check on whether you have been paying the right amount of federal income tax.

That advice holds not only for people with large incomes and complicated investments, but for everyday wage-earners who haven't checked lately on the progress of their income and withholding taxes.The idea is simply to determine whether you have paid too much or too little so far toward the eventual bottom line on the tax return that will be due April 15.

If the answer is too little, you may be in danger of incurring interest charges and penalties from the Internal Revenue Service.

If the answer is too much, you may want to consider asking your employer to reduce your withholding tax for the last few paychecks of the year.

Less withholding now will reduce the size of the refund you stand to collect next spring. That may not appeal much to people who use overwithholding as a type of "forced savings" plan.

But if you are going to be due the money a few months from now, why not collect it sooner and put it to work for you, rather than leaving it "on deposit" with Uncle Sam at no interest?

Perhaps the extra take-home money in December might help you to pay for holiday gifts and activities without having to borrow at high credit-card interest rates.

The exercise of calculating the status of your tax payments does not have to be especially complicated. But experts on the subject say it needs to be done with care to avoid a misstep.

Many people can start with their most recent pay stub, which should give them a pretty good idea of what their total wages and salaries will be for the year.

If your other income and deductions, such as investment interest received and mortgage interest paid, has not changed drastically since last year, you can use the numbers on your 1987 return as a basis for estimating what your 1988 taxable income will be (remembering that some deductions, such as for consumer interest expense, will be less generous for 1988).

Then you can compute your projected 1988 tax liability using the tax tables for the year, which may be available from your employer, a financial institution where you do business or your local library.

If it looks as though your withholding is going to fall short by a significant amount, further action may be warranted.

To avoid penalties and interest, the rules require that your withholding (and any quarterly estimated or other advance payments) satisfy one of two standards.

It must equal either 100 percent of what you owed for 1987, or 90 percent of what will be due for 1988.

Suppose you had a windfall this year, substantially increasing your taxable income, and you find that you are not likely to satisfy either of those tests.

"If you're able to adjust withholding, you can solve the problem," says William Brennan, an adviser on investment and tax planning with the accounting firm of Ernst & Whinney.

"Just arrange with your employer to withhold the amount needed to `catch up.' Withholding is deemed to have been paid in evenly throughout the year, no matter when it's actually withheld.

"In this way, you may be able to avoid interest and penalties entirely."

Another way to close the gap: Step up your deductible activities, such as charitable contributions, to reduce the amount of income that will be subject to tax.