The Tax Policy Center is offering an online calculator to help taxpayers understand the impact of the fiscal cliff on their finances.

The think tank, which operates under the auspices of the Urban Institute and the Brookings Institution, shows what would happen to different types of taxpayers under the various scenarios under consideration in Washington. Under one scenario, it shows what would happen if the current tax rates and the AMT patch were in place for next year. Under a second “fiscal cliff” scenario, the calculator shows what would happen to the taxpayer’s finances next year if all the tax cuts enacted over the past decade expired and the new taxes associated with the health care reform law were in place, but there was no AMT patch or payroll tax cut.

A third scenario demonstrates what would happen with the taxpayer’s taxes under the Senate Democrat’s plan for 2013, while a fourth scenario indicates what would happen under the Senate Republicans’ plan for next year.

Users can input their information using various examples, such as a taxpayer who is married, under age 65 and with no children, or someone who is married and has one child in college. Or they can create their own example.

The online calculator provides a handy way to gauge how you and your tax clients might fare, depending on the outcome of the negotiations, and do some tax planning for your clients using what-if analysis. Of course, what the lawmakers and Obama administration in Washington ultimately decide to do is anybody’s guess.