Write offs are a scam because of this big gray area. The rules get complicated fast and it quickly becomes less clear whether you can or not, and they’re difficult to automatically check. So …. You can write off any expense, up until you get caught. Remember this next time you see a politician wanting to reduce funds for IRS audits.
For all the dread people fear at the word “audit”, remember who really has the most to fear, and it’s not you
FYI - my own experience with the dreaded IRS enforcement was …. Receiving mail that something was wrong on my tax form and if I agreed, they calculated how that would change what I owe. I took a look, and “yep, my bad”, and paid the correct amount. No fees, no penalties, minimal paperwork, no threats, no bullying. Just facts. Ooooh, nightmares