What are red flags that mean I need a CPA?

Red flags that signal you need professional help: you received an IRS notice or audit letter, you have unreported foreign bank accounts, you sold a business or significant assets, you have complex pass-through income from a partnership or S-corp, you owe back taxes with penalties accruing, or your return involves the Alternative Minimum Tax (AMT) and incentive stock options. DIY software can't substitute for a professional's judgment in these cases.