For taxpayers that make estimated tax payments throughout the year, the payment for the fourth quarter is due on January 15 of the next year. Even though this payment is made in the following year, it is still credited as a payment for the tax year in which it applies. But, if the taxpayer lives in an "income tax state" (a state with its own income tax, like Arkansas or Louisiana, but not Texas) and makes estimated tax payments to the state, there is a catch to when these payments are deductible on a Federal return.
Allowable itemized deductions for individuals on a Federal 1040 include state and local taxes paid. These taxes include income, real estate, and personal property taxes as well as some other taxes paid to a state or local government. The deductible portion of these taxes is the amount actually paid during the year, not amounts assessed or paid in other years. Here are a few examples:
Bob, who does not live in an income tax state, pays his personal property taxes for 2012 in October of 2013 for $500. At the same time, he receives his assessment for 2013 of $600 which will be due in October 2014. Bob's deduction for personal property taxes in 2013 is $500, because that is what he actually paid even though it was related to the previous year. The $600 will be deductible to him in 2014 when it is paid.
Peggy lives in an income tax state and makes state estimated tax payments quarterly. In January 2013, she made her 4th quarter payment for 2012 for $500. Then, in April, June, and September of 2013 and in January 2014 she made quarterly payments of $600 each for her 2013 state taxes. Peggy's state tax deduction on her Federal return for 2013 is $2,300 ($500 + 3 $600 payments) which is the total of the payments made during 2013, even though one of them was related to a previous year.
This example leads us to the point of this article. If Peggy makes her state fourth quarter payment for 2013 in December 2013 instead of January 2014, her state tax deduction on her Federal return will be $2,900 instead of $2,300. As a result, her Federal tax liability would be decreased slightly because of the added deduction. It is for this reason that taxpayers living in income tax states should always consider paying their final estimated tax payment before the end of the year.
But, as is usually the case, there are caveats with this plan - the Alternative Minimum Tax and the time value of money.
Taxpayers subject to the Alternative Minimum Tax (AMT) will not realize the benefit of paying their state estimated tax payment early because those payments will be added back as a preference item on Form 6251. Therefore if taxpayers are close to or already subject to the AMT, they should make their payments as scheduled (not early).
Taxpayers must also consider the time value of money when paying estimated tax payments early. For example, if the funds needed to make the estimated tax payment will be accessed by selling investments at a gain, then the net effect of the transaction might be zero because the additional benefit from the payment could be offset by the additional income recognized from selling the investments in the same year. Furthermore, the funds used to pay taxes earlier by 15-30 days may lose investment earnings which could be large if the estimated tax payment is large.
In closing, taxpayers should consider making their 4th quarter state estimated tax payment in December (now!) as long as they are not subject to the AMT and they have liquid funds to make the payment without creating additional income.