4. Validate your 1040 (usually if you have wages), Schedule E (rental) and Schedule C (business). 5. Add up all your sources of income on the above 3 forms and make sure it is accurately reflected. 6. Look at every line in the form for deduction and check if you have something for that particular line and if not; you should be asking your CPA about it. For example, Schedule E has several lines for expenses including depreciation. If all those lines are blank then alarm bells should be going off in your head.