One of the most overlooked things that get you audited is getting paid for work on a 1099 and either never getting the 1099 or forgetting to file it on you taxes.
Other things in this same category is investment returns, if you receive capital gains on a mutual fund and fail to file the 1099, you will get audited because the investment company will file one on their side.
That got my wife and I audited one time for just this reason.
I would think long and hard on any income you received that might not have been accounted for in your tax filing.
I just had SS income, small amount from Fidelity and W-2 for part time job. Yet I am being reviewed.
I only have one employer and took some cash from a 401k. Both were included. I don’t have any other sources of income.