The most important rule is tracking expenses separately for each property. If you own three rentals, you need to see income and expenses for each one individually. Lumping everything together makes it impossible to know which properties are profitable and which are dragging down your portfolio.

Set up your accounting software with each property as its own tracking category. In QuickBooks Online, you can use the Location or Class feature to separate properties. Every transaction gets tagged to the specific property it relates to. When tax time comes, you need a Schedule E for each property anyway, so the separation is required from the start.

Common rental expense categories include repairs and maintenance, property management fees, insurance premiums, property taxes, mortgage interest, utilities you cover, HOA fees, landscaping, cleaning between tenants, advertising for vacancies, and legal or professional fees. Keep these categories consistent across all your properties so you can compare performance.

The distinction between repairs and capital improvements matters significantly for real estate owners. A repair maintains the property in its current condition and is fully deductible in the year paid. A capital improvement adds value or extends the useful life and must be depreciated over time. Replacing a broken faucet is a repair. Replacing all the plumbing is an improvement. Getting this classification wrong affects your taxes for years.

Keep receipts for everything. If you’re audited, you need documentation showing what the expense was for and which property it relates to. Digital receipt management through an app or cloud storage works better than paper folders that get lost or damaged.

For mileage, track trips to properties for repairs, showing units, or meeting contractors. The standard mileage rate applies to rental property travel. A mileage tracking app makes this automatic instead of trying to reconstruct trips months later.

If you use property management software like Appfolio or Buildium, those systems track income and some expenses. But they’re designed for property management, not accounting. You still need to reconcile against your bank accounts and credit cards to catch expenses paid outside the management system.

Having a dedicated bank account and credit card for your rental properties simplifies everything. Personal and rental expenses mixed together means sorting through statements trying to remember if that Home Depot receipt was for your house or a rental unit.

Review your books monthly rather than waiting until tax season. It’s easy to forget about a repair you paid for in March when you’re doing taxes the following year. Working with a San Diego bookkeeper who understands rental properties means the property-level tracking stays accurate and your Schedule E preparation is straightforward instead of a scramble every spring.