Every state with an income tax requires that you pay the tax throughout the year, just as the IRS does. This is done either through withholding from your paycheck - if you are an employee - or through quarterly estimated payments if you are self-employed, retired, or you are an employee but have not increased your withholding to cover the taxes you will owe on your investment income.

If you are stuck in the AMT, you are getting no benefit from your state income taxes paid - they simply are disallowed as a deduction in computing the Alternative Minimum Tax. But if you could move some of your deductions to a year when you are not in the AMT, you could achieve real tax savings - up to the 35% depending on your tax bracket.

Essentials of state tax payments

There are two essential things to remember in planning your state income tax payments in order to reduce your AMT

One is that no state requires you to pay in 100% of your state tax liability - the required percentage generally is 80% or 90%. If you don't pay in this minimum required amount you may be subject to an underpayment penalty, which usually is calculated in a manner similar to interest.

Second is that if you make quarterly estimated tax payments, the fourth quarter payment generally is due on January 15 - for example, January 15, 2011 for the fourth quarter installment of your 2010 taxes. This is the way the IRS works, and most states follow this pattern.

Control over that last portion of state taxes due

Remembering the above key facts, the AMT-saving strategy is to look at the control you have over the payment of this last portion of your state taxes - the fourth quarter installment, if applicable, and/or the last 10% or 20% you will owe. Since you have the choice of paying a portion of your state income taxes either in December of the current year, or in January or even April of the following year, the decision on when you write out the check to pay these taxes will have a direct impact on the AMT you will pay.

By having more of your state income taxes paid in a year when you are not in the AMT, you will achieve real tax savings.

An example

To illustrate how this works, assume that you expect to be in the AMT in 2010, that your total 2010 state taxes will be $15,000, and that you expect not be in the AMT in 2011. If you could defer paying just 10% - $1,500 - of your 2010 state income tax until 2011, this could save you $500 or more depending on your tax bracket. If you could defer $3,000, your savings would be over $1,000, and so on. Note that even if you do end in the AMT again next year, continuing to execute this strategy will mean that you will achieve this Regular Tax benefit in the first year that you are not in the AMT. With the Democrats pushing for higher income tax rates, this becomes more and more a real possibility.

What you need to do to evaluate this AMT-saving strategy

Check on your state's website to determine the minimum percentage of your taxes that have to be paid in by December 31. It likely is 80% or 90%. Also check the rules for estimated payments and the forms that you will need to do this. Then, using an AMT planning model, try putting different numbers in the model for your state tax payments, and you quickly will see how much you might be able to save by reducing your AMT.

Good luck with your planning!