If you have less than 26 million in revenue you can choose to not keep an inventory and treat it using cash accounting. When you buy oil filters, that’s an expense that you book. Lets say that happened in 2023. Then you sell filters in 2024. The expense is booked in '23 and the profit in '24. Vs accrual and managing inventory, the cost is booked when it’s sold. Most shops should have no too low inventory because you buy parts when a car comes in. You probably stock oil, filters, bulbs, and some smaller items. Not a whole lot.

We use MaxxTraxx shop management. For us it’s $588 a quarter, it handles customer checkout, sales tax, and inventory etc. IK other shops use AllData’s shop software which is good too. You probably already pay them for repair data as well. Many shops don’t really use an inventory system since most shops are below revenue rules from IRS to maintain an accurate one. So you could be ok, especially if you use cash accounting.