Form 6251 is an IRS form used to determine whether taxpayers owe an additional tax called the Alternative Minimum Tax (AMT). The AMT was first introduced in 1969, with the aim of making sure the wealthy pay their fair share of taxes. Over the years, however, changes in tax law have meant that fewer and fewer taxpayers have been subject to this additional tax burden.

The most recent changes to the AMT were part of the Tax Cuts and Jobs Act, signed into law in 2017. This greatly reduced the number of taxpayers required to pay the AMT. In 2023, however, the IRS raised the AMT to $81,300 for individuals, and $126,500 for couples who are married filing jointly.

Form 6251 is used to calculate the amount of AMT that an individual or a couple must pay. It's important to understand that the AMT is a separate tax system, in which you are required to calculate your taxes a second time, taking into account different sets of rules for deductions, credits and adjustments. If your AMT calculation yields a higher tax burden than your regular income tax calculation, you will be required to pay the additional tax.

It's important to note that the AMT is a complex system, and consulting with a professional tax preparer is always recommended. Taxpayers are encouraged to complete Form 6251 correctly, to avoid penalties and fines.