I'm confused by this. I don't recall what I did 7 years ago when I used to shop (probably just considered it a hobby and didn't claim anything) so this will be my first time filing taxes using mystery shopping as a business. I freely admit that I could be wrong, but here's my logic:
If I run an office and I decide I need a new filing cabinet for my office, there is no IRS rule that says I have to choose the least expensive filing cabinet in order to deduct it as a business expense.
If I take a client out to lunch for a meeting, there is no requirement that I and my client have to order the least expensive items on the menu in order to claim it as a business expense.
If I am required to order a meal in order to evaluate a restaurant, and the company pays a flat fee and does not reimburse, why would there be a requirement that I order something that costs less than the fee, in order to claim it as a business expense?
If the company reimburses expenses up to a certain amount, obviously I can't claim the portion of the meal that they reimbursed as a business expense, but if I had additional expenses then why not?
The expenses only balance out the income that I make, in terms of tax liability. I'm not getting extra money from the government to pay for my extravagant meal, I'm simply not paying taxes on some of the money I earned from the meal that I paid for in order to evaluation the restaurant. What IRS auditor is going to say "Why did you order the salmon entree when you could have had the chicken?"
We are all here on earth to help others....What on earth the others are here for I don't know.
--W. H. Auden