I'm sorry to hear about the situation with the startup company. If you paid Alternative Minimum Tax (AMT) due to an exercise of Incentive Stock Options (ISOs) and the company went defunct, you might be able to claim a tax break. You can potentially qualify for an AMT credit, which allows you to offset future regular tax liability. This credit arises from the difference between the AMT you paid due to the ISOs and the regular tax that would have been due without the ISOs exercise. If the company went defunct and the ISO shares became worthless, you might be able to claim a capital loss on your tax return, which can offset capital gains or, to a limited extent, ordinary income. Keep in mind that tax situations can be complex, and I'm providing a general overview. It's essential to consider the specifics of your case when determining any tax breaks or credits available to you.