The IRS requires you to allocate expenses between personal and rental use when you use a property for both purposes. What you can deduct depends on how many days it was rented versus how many days you used it personally. Your books need to reflect this split accurately.

Start by tracking every day the property is occupied and categorizing who used it. Rental days are when paying guests stay. Personal use days include when you stay, when family stays, or when anyone stays at below-market rates. Vacant days and days spent solely on maintenance typically don’t count as either. Keep a calendar or log throughout the year rather than trying to reconstruct it later.

Calculate your rental use percentage by dividing rental days by total days the property was used. If the property was rented 90 days and you used it personally 30 days, total use is 120 days and rental use is 75%. This percentage applies to shared expenses.

Shared expenses are costs that apply to the whole property regardless of who uses it. Mortgage interest, property taxes, homeowner’s insurance, HOA fees, utilities, and general repairs fall into this category. If your annual insurance is $2,400 and rental use was 75%, you allocate $1,800 to rental expense and $600 to personal use. The personal portion is not deductible as a rental expense.

Direct expenses don’t need allocation because they clearly belong to one category or the other. Airbnb fees, cleaning between guests, guest supplies, and professional photography for listings are rental expenses. Groceries you buy for your own stay, personal toiletries, and entertainment during personal visits are personal and shouldn’t appear in your rental expense tracking at all.

In your accounting software, set up the property as its own tracking category or class. Create separate expense accounts or use sub-accounts to distinguish rental costs from personal costs. When you pay an expense that needs allocation, either split it at the time of entry or make an adjusting entry at year end once you know the final day counts.

For vacation rental operators in Santa Fe who use their property part of the year, this tracking is especially important. The rental market is seasonal, and the mix of personal and rental use can shift year to year. Your books need to capture what actually happened, not an estimate.

Keep documentation beyond just the numbers in your accounting software. Save a copy of your use calendar, booking confirmations, and notes on repairs or improvements. If you’re ever asked to substantiate your deductions, you’ll need to show how you determined the allocation.

Be consistent with your methodology. Pick a reasonable approach for allocating expenses and stick with it. Changing methods year to year or picking whichever calculation gives you a better deduction invites scrutiny.

If tracking the split feels like too much on top of managing the property, working with a QuickBooks bookkeeper in Santa Fe who understands rental properties can save you time and help ensure your allocations hold up. Getting the books right during the year is easier than reconstructing everything at tax time.