"Audit" is a scary word but it just means, "show us how you got these numbers." These agencies aren't out to ruin your life, they just want your tax return to be a good representation of what happened. It's annoying but not that difficult.
How long it takes depends on how organized your records are. Whatever state they are in, it's doable. It comes down to what numbers on your return you want to defend; there may be some where you decide getting all the receipts organized is not worth the amount of money that a particular expense saved you.
If you receive a notice or letter from the IRS or a state Department of Revenue on a tax year, don't hesitate. Scan or photograph the letter (front and back of each page) and forward it to us: firstname.lastname@example.org.
After we review it we can have a chat and advise you on next steps.