(FORTUNE Magazine) – Dear Mr. Statistics: I am a rich femme, aged 70, who has just discovered she is a victim of sex discrimination and seeks revenge. The news is centered on my IRA account, currently worth $3 million. Not now needing these funds to sustain myself, I would just as soon let the whole bundle continue growing at its customary average rate of 6% per annum tax-free. As everybody knows, however, you have to start withdrawing funds from IRAs -- and to pay income taxes on the amounts withdrawn -- beginning soon after age 70 1/2. The amount you have to withdraw each year reflects your remaining life expectancy as registered in actuarial tables published in IRS Bulletin 590. The tables state that at 71 my own participation in planetary events is expected to terminate in 15.3 years, which means that in the first year I must withdraw and pay taxes on at least $196,078 ($3 million divided by 15.3). Okay so far. I can live with the withdrawal requirement. What put me into shock was discovering that Bulletin 590 is all lies. Its life expectancies do not distinguish between women and men. As any actuary will tell you, I have a life expectancy almost four years greater than that of a male my age. So why can't I divide my $3 million by a larger number of years (which would reduce the total needing to be withdrawn and taxed)? Incidentally, what is this deal costing me? -- READY TO SCREAM

Dear Ready: The decision to defy nature and move to unisex actuarial tables was made by the Reaganites in Treasury rulings that took effect in 1986 and generated virtually no opposition. The reason for the switch was fear of the feminist movement, which was demanding unisex tables in the name of equality and winning in the courts. In the absence of such tables, pension plans had been forcing long-living female annuitants to either pay larger premiums or receive smaller annual payouts. It seems not to have occurred to the movement that in many contexts unisex tables discriminate irrationally against women. Costing out this discrimination is not easy, but we shall try. We begin by adjusting the IRS unisex tables to reflect the real-world gender gap in life expectancy at each age. (According to the National Center for Health Statistics, an average woman of 70 will live 3.5 years longer than an average man; however, this gap shrinks to 1.2 years by age 85.) Next we create a spreadsheet depicting the tax payments you would make over the next ten years in two different scenarios. In Scenario No. 1, your withdrawals and taxes reflect the unisex tables; in Scenario No. 2, they are driven by our ''real- world'' tables. In both cases, we assume that your marginal tax rate is 31% -- also that funds left in the IRA continue to earn 6% a year.

You have reason to scream. Over the decade, the unisex tables will force you to pay taxes whose net present value (assuming a 6% rate of discount) is about $22,000 more than those that would be required under our real-world gender-gap tables. Also, your IRA in 2003 will be worth only about $2,200,000 -- some $300,000 less than it would be with our tables. While you are getting burned, similarly situated men of your age will be making out like bandits in their IRAs. An interesting question is whether they would know whom to thank.