The return of the so-called marriage penalty could cost many couples more than $2,000 in higher 2013 taxes if Congress doesn't get its act together and fix the fiscal cliff.

As a result of the Bush tax cuts, married couples get a standard deduction that's exactly twice that of individuals. And the income ranges for the 10% and 15% tax brackets are also doubled. Prior to 2001, many married couples had paid a "penalty" because their standard deduction and income tax brackets were less than twice those of singles.

Next year the imbalance could return. While the standard deduction for single filers should rise to $6,100, married couples would receive a deduction of only $10,150 if lawmakers don't extend the provision, according to estimates by the Tax Foundation. To erase the marriage penalty, it would have to be $12,200.

Married couples would also be moved into higher tax brackets more quickly. Individual taxpayers would be in the 15% tax bracket until they hit $36,250 in taxable income, but married filers could be pushed above it after only $60,550 in income, as opposed to $72,500.

The marriage penalty never went away for higher tax brackets above 15% -- and that would continue to be the case. Even if the Bush tax cuts are extended, the 25% bracket would end at $87,850 for singles, but only at $146,400 for joint filers. And the highest bracket starts at the same income level regardless of whether the filer is a married couple or a single person.

Related: Going over the Cliff - what changes, what doesn't

Married couples benefiting from the Earned Income Tax Cut would also get hit if the fiscal cliff isn't addressed. The last two administrations raised the income threshold at which the credit begins to phase out for married couples to $5,000 above the amount for individuals.

Of course, the marriage penalty is only one of a bevy of provisions that are set to expire after 2012 so exactly what both married couples and single filers will pay next year remains up in the air.