By contrast, the pot of money from the traditional I.R.A., earning an after-tax rate of 5.4 percent, would give him $475,000 in payments over his lifetime.

This can be seen by comparing the 2005 pre-tax low-income cut-off rate of 15.3% with the after-tax rate of only 10.8%.

"The average investor in the 28 percent or 31 percent tax bracket can earn higher after-tax rates in a taxable money fund," Ms. Bugbee said.

Aetna said the Prudential unit's losses were running at an annual after-tax rate of $200 million, double the losses expected by some analysts.

Given the price it did sell for, for someone in a 28 percent federal income tax bracket, the long-run after-tax annual rate of return will be 7.4 percent.

A return may be adjusted for taxes to give the after-tax rate of return.

The interest rates payable reflect after-tax effective rates (assuming a 35% tax rate) equivalent to the dividend rate paid on the preferred stock.

Hence we argued that, for people already in work, changes in after-tax rates have only a small effect on hours of work supplied.

"I would argue that the real after-tax rate has to be half a point above that average in order to slow the consumer and the economy down," he said.

These interest rates equate to after-tax effective rates (assuming a 35% tax rate) equivalent to the dividend rate paid by C corporation participants.