>>FWIW, Marshal and I are fairly sure that if we were ever audited, we'd wind up getting money back.

Depends on your auditor. Some of them dig and dig until they find something. They start with car expenses and entertainment costs. If they don't find anything there, they'll dig elsewhere. They also know the sorts of expenses for which you may not have receipts or invoices or for which you may not have quantified personal use. A couple of years ago I watched an auditor ask for 100 receipts/invoices. When the business triumphantly produced all 100, he simply asked for another 100. And another. And he would have kept doing it (at huge inconvenience to the business) had a partner at E&Y not challenged the auditor to justify reasons for giving this business "special" treatment. He chose to back down rather than risking escalation but actually he had every right to do this as long as he pleased. And the more time he invested in this investigation, the more skin he had in the game to find something. Obviously this may not be so relevant to an individual who has hundreds rather than thousands of receipts/invoices to maintain, but still something to consider.