Categorizing is the part of bookkeeping that eats evenings. The rules are simple; the volume is the problem. Here are the rules, the judgment calls, and how to stop doing it by hand.
The only rule that matters
An expense is deductible if it is ordinary (common in your line of work) and necessary (helpful and appropriate). Category choice affects which line it lands on, not whether it is deductible, so do not agonize over office expense versus supplies.
The gray areas
- Meals: 50% deductible when business is discussed with someone. Solo lunch at your desk is not deductible.
- Phone and internet: deduct the business-use percentage. Keep it consistent.
- Equipment: items under $2,500 can be expensed under the de minimis safe harbor; above that, depreciate or take Section 179.
- Clothing: deductible only if it is not suitable for everyday wear (uniforms, safety gear).
- Personal on the business card: owner draw, not an expense.
- Transfers and card payments: not expenses at all. Record as transfers or you double count.
How AI categorization works
ProfitBooks looks at the description, amount, your industry, the vendor's history across many businesses, and your own past corrections. It assigns a category and a confidence score. You set a threshold: above it, the transaction is finalized automatically; below it, it waits for you. Every correction raises confidence on similar transactions.