The President was right to veto the marriage penalty legislation Congress sent to him, but not for the reasons he stated. The chief shortcomings of the bill are not that it is too expensive or slanted toward wealthier couples, but that it leaves much of the unfair penalty in place. At the same time, it actually increases the rarely discussed marriage bonus.

Yes, the marriage bonus, the one that almost 50 percent of married couples receive for no reason other than marital status and is just as unfair as the marriage penalty. The exaggerated rhetoric on the topic of marriage and taxes leaves many couples bemoaning their penalty, when actually they pay less in taxes than they would if single. The legislation vetoed by the White House addresses only half the problem, while making the other half worse.

Both marriage penalties and bonuses are the unintended consequences of a complicated tax system that tries to balance often-conflicting goals. The combination of progressive taxation, where higher incomes are taxed at higher rates and taxing married couples as a single unit leads to inequities in the treatment of couples and singles. The resulting peculiarity is that almost all married couples face different tax liabilities than they would if they were earning the same amount but were single.

Far from punishing all married couples, this arrangement creates almost as many winners as it does losers. Take for example an individual earning $70,000 who marries a spouse who does not work. The couple's standard deduction increases from the $4,400 deduction for singles to the $7,350 joint deduction. They also qualify for a second personal exemption and wider tax brackets applied to the same single income. All these changes allow more of the worker's income to be taxed at a lower rate. Merely by qualifying as married filers, the couple receives about $4,000 in tax breaks.

Since couples are treated the same in terms of taxes, their taxes are the same as for another married couple with two earners making $35,000 apiece. This dual-earner couple is penalized by the joint standard deduction, which is less than double the single deduction, and progressive taxation, which pushes more of their combined income into a higher tax bracket. As a result, they pay roughly $1,500 extra in taxes.

It is, in fact, difficult to conceive of why taxpayers should pay either more or less based on their decision to wed -- yet almost all of them do. The Treasury estimates that while 25 million couples are hit with an average annual penalty of $1,100, 21 million couples receive bonuses of a slightly greater amount.

If Congress is serious about addressing tax unfairness, it has chosen a poor strategy to eliminate the marriage penalty. The bill sent to the president increases the standard deduction and widens some income tax brackets for joint filers to eliminate part of the penalty. But not only do these changes fail to remove the penalty entirely, they further reduce taxes for those couples already receiving bonuses.

The $70,000 single-earner couple would receive an additional bonus on top of their $4,000 tax break. This is hardly an improvement in tax fairness -- particularly at a price tag of $290 billion over the next 10 years, much of which would go to those not being penalized.

A better approach, and one used in most developed countries, would be simply to tax individuals rather than couples. Under such a system, individuals earning the same incomes would pay the same in taxes, and their liabilities would remain unchanged by marriage.

Addressing a failure of the current legislation, individual taxation would fully eliminate all marriage penalties. And in keeping with principles of fairness, undeserved marriage bonuses would be removed as well. By wiping out both penalties and bonuses, individual taxation would be far less expensive than the current proposal, costing virtually nothing to the Treasury.

Changing the tax code is always challenging, because taxpayers are suspicious that benefits will accrue to somebody else at their expense. If Congress successfully overrides the president's veto, as it will surely attempt to do, singles will certainly have cause to complain.

If the goal of marriage penalty legislation is to rid the tax code of unfair treatment of married couples, it will not be achieved by doling out tax cuts indiscriminately to married couples whether or not they are penalized.

On the other hand, taxing individuals would simplify the tax code while ridding it of unjustifiable marriage penalties and subsidies alike. If Congress chooses to move forward with its boon for married couples, it should brace itself for the ensuing flood of complaints about the resulting "singles tax penalty."