I have written recently about the choice of averaging techniques to determine the federal tax on lump sum distributions from a pension plan. The old 10-year averaging method has been replaced by a new and generally less favorable five-year formula. However, anyone who was at least 50 years old on Jan. 1, 1986, has the option of selecting either method, but must use 1986 tax rates if 10-year averaging is chosen.

If you fall in this over-50 group, Commerce Clearing House has come up with some numbers that can save you the chore of working out both computations to determine which is more favorable. According to their calculations, for the 1987 tax year 10-year averaging is more favorable than five-year averaging as long as the adjusted taxable amount of the distribution is \$741,600 or less. For larger distributions, you'll come out ahead with five-year averaging.

For distributions in 1988 and later years, despite the reduction in tax rates from 1986 levels, 10-year averaging still provides a lower tax for an adjusted taxable amount up to \$473,700. If the taxable amount of the distribution goes over that ceiling, five-year averaging is substantially more favorable. Further, unless the distribution total exceeds \$473,700, there is no advantage to be gained by postponing receipt, since use of the 1986 tax rates in tandem with the 10-year method is required regardless of the year of distribution.

The option of deferring tax altogether by rolling over the distribution to an IRA continues to be available under the new tax law; but the tax savings from averaging will not be available when the money is later withdrawn from the IRA.

Last year, I purchased a three-year subscription to the Wall Street Journal. Pursuant to an IRS ruling, I was allowed to deduct only the value of a one-year subscription. Will I be allowed to include the value of a one-year subscription to the Journal this year as a miscellaneous deduction even though the expense was actually incurred in 1986?

You can deduct more of the subscription cost this year, even though the money was paid in 1986 -- but not exactly in the way you describe. Instead of the "value" of a one-year subscription last year, you should have deducted one-third of the actual cost of the three-year subscription. For 1987, then, if you itemize and your miscellaneous expenses exceed the 2 percent floor, you may claim another one-third of the cost; and you can repeat the process for 1988. But the total claimed may never exceed the actual amount paid for the three-year subscription. If in fact you claimed the "value" of a one-year subscription last year, then for 1987 you should include half of the remaining cost, and take the other half on your 1988 return.

In your column of July 13, in reference to two types of IRA contributions, you say that "The rule on withdrawals requires that you consider all IRAs as a single account at that time." This is contrary to the information I have received from more than one financial institution. Their instructions have been to the effect that if one has multiple IRA accounts at the time one qualifies for withdrawals, he or she may withdraw any of these accounts at any time. The only consequence is that income tax must be paid on all accumulated interest and on those individual contributions that were tax-deferred at the time.

You may not be happy with this answer. In the good old days (like last year) when all IRA contributions were tax-deferred, your financial institutions were correct -- and are still partially correct. After age 59 1/2, if you have more than one IRA, you may withdraw funds from whichever account you wish. But if you have made both tax-deferred and taxable IRA contributions, you must compute the ratio of taxable to nontaxable withdrawals based on the total amounts in all your accounts regardless of the tax status of the particular account from which the funds are withdrawn. And when you reach age 70 1/2, you must consider all IRAs as one account when determining the minimum mandatory annual withdrawal.Abramson is a family financial counselor and tax adviser. Questions of general interest on tax matters, insurance, investments, estate planning and other aspects of family finances will be answered in this column. Advice cannot be given on an individual basis. Address all questions to E.M. Abramson, The Washington Post, Business News, 1150 15th St. NW, Washington, D.C. 20071.