I exercised stock options from my company in 2021 but I have not sold them. How do I report on this for the 2021 tax year (filing in 2022)?

When you exercise and hold an Incentive Stock Option (ISO) there is no taxable event for ordinary tax. You merely purchased the stock, and your cost basis is the strike price. However, for AMT purposes, the difference between what you paid and what the stock is worth at the time of exercise is a "preference item" for AMT.  What that means is that amount is added to your income for the AMT calculation. For this reason, the details of the ISO exercise are reported on your tax return in the year of the exercise.

When you exercise stock options and held but didn't sell, enter this in TurboTax Online as follows:

Incentive Stock Options (ISO) for Form 3921 are entered in TurboTax Online under:

1. Federal Taxes
2. Wages & Income
3. Investment Income
4. ISO Exercise and Hold
5. Click Start/Revisit

In the desktop version, enter under Stocks, Mutual Funds, etc. and follow the interview.