The IRS generally doesn’t care about your credit card rewards—points, miles, or cash back—but there are some exceptions. The main thing you need to be aware of is when you charge business expenses to a cashback credit card, you can only deduct the net expenses after you’ve received any cash back.
For example, if you earn $20 in cash back credit card rewards for $1000 worth of computer equipment for your business, you can only deduct your net cost of $980. The IRS views these cash-back rewards as a post-purchase discount, and you have to consider it when claiming a deduction, just as if you had used a coupon to save $20 off of your purchase, or received a $20 rebate.
