For all the tax planning that goes on for both businesses and individuals, many people still don’t know how much they will be paying—until they begin the process of filling out forms. This, of course, can lead to a few unwelcome “surprises” involving your tax liability.

The good news: Last year, the American Institute of CPAs, the world’s largest association representing the accounting profession, with nearly 377,000 members in 128 countries, unveiled a tool that aids you in predicting your tax obligation any time of the year. It’s free. It’s easily accessible. It’s incredibly user-friendly. And it’s called the Total Tax Insights Calculator.

The Total Tax Insights Calculator not only calculates estimated federal, state and local tax obligations, it also provides insight on how much is being paid annually in taxes that are generally not documented in individual tax returns. These often-unacknowledged taxes include point-of-sales tax on store-bought goods and monthly bills. Currently, the program is able to factor in more than 20 taxes at the federal, state and local levels for more than 3,000 U.S. counties. It is important to keep in mind that since all taxes are not represented, the calculator is purely providing an estimate.

There are only a few mandatory questions you must answer to generate your tax estimate. To get started, you must first choose your location from the website’s interactive map (totaltaxinsights.com). Once you have made that selection, the calculator requires you to enter the county in which you live, marital status, federal adjusted gross income and number of dependents. Though this is all the information you need, you are also able to dig much deeper into your taxes. There are dozens of other fields you can fill out to help you better predict your tax liability. These options are divided into four groups:

Income Information: includes medical expenses, mortgage interest and charitable contributions.

Your Home: average monthly bills, including electricity, gas and cable.

Personal Expenses: consists of cell phone bill, gas for your car, alcohol purchases and some travel expenses.

Other: store-bought goods such as groceries, clothes and household products.

Once you have entered as much information as you wish, the calculator presents your estimated annual tax liability in a variety of ways. It provides a list, broken down into the four categories, displaying dollar amounts of taxes paid in each category. Also, if you prefer a more visual representation, a Tax Breakdown pie chart illustrates how much of the taxes you pay fall into each of the four areas.

This tool may come in handy when financial planning or making important life decisions. Perhaps you are contemplating a move. You can calculate your tax liability in your current city then determine the liability for the relocation city you are considering. Or, if you discover how much tax you are paying on gas, it may influence you to purchase a car with better mileage. Also, aside from allowing you to see your expected tax liability, the Total Tax Insights Calculator aims to educate you on the taxes you are paying. The website features a glossary of tax-related terms, as well, plus links to information on the different taxes that are represented.

Remember that knowledge is power.