What Happens When You Skip Depreciation on Mixed-Use Property?

When property is used for both personal and business or rental purposes, depreciation must be allocated to the business or rental portion - and the IRS does not forgive the portion you failed to claim. Under the "allowed or allowable" rule in IRC Section 1016(a)(2), your cost basis is reduced by the greater of depreciation actually taken or the amount you were entitled to take, whether you claimed it or not. Skipping depreciation on mixed-use property does not preserve basis - it creates a phantom gain on sale. The mechanics and the recovery options are worth understanding before a disposition forces the issue.

The Allowed or Allowable Rule

IRC Section 1016(a)(2) requires that adjusted basis be reduced by the amount of depreciation "allowed or allowable" - whichever is greater. The word "allowable" is the problem for taxpayers who skipped deductions they were entitled to take.

If you owned a mixed-use property for ten years, used 60% for business or rental, and never claimed depreciation on that 60%, your adjusted basis on sale is still reduced as if you had claimed it every year. The IRS does not reward the omission. You lose the deduction and you still pay tax on the phantom recovery.

How Mixed-Use Allocation Works

For property that is partly personal and partly business or rental use, only the business or rental percentage is depreciable. The personal-use portion has no depreciable basis and generates no loss on sale. The allocation method must be consistent and supportable - typically square footage for real property, time-use logs for vehicles and equipment.

Common mixed-use situations:

A home office under IRC Section 280A - the business-use percentage of the home's basis is depreciable over 39 years (nonresidential) or as part of the residential structure depending on the structure type and use
A vacation property that is also rented - rental days versus personal days determine the deductible and depreciable percentage, subject to the Section 280A limitation rules
Vehicles used for both business and personal driving - the business-use percentage of the vehicle's cost is depreciable, subject to the luxury auto caps under IRC Section 280F

The Pitfall on Sale

When mixed-use property is sold, the gain calculation uses adjusted basis - original cost reduced by all depreciation allowed or allowable on the business portion. If depreciation was never claimed, adjusted basis is still reduced by the amount that should have been claimed. The result is a larger taxable gain than the seller anticipated, with no prior-year deductions to offset it.

For residential rental property, any depreciation actually taken or allowable is subject to Section 1250 unrecaptured gain, taxed at a maximum federal rate of 25%. Skipping the deduction does not avoid this rate - the allowable amount is still recaptured on sale even if it was never deducted.

Correcting Missed Depreciation

The IRS provides a mechanism to catch up missed depreciation without amending prior returns. Revenue Procedure 2002-9 and the automatic change procedures under Revenue Procedure 2015-13 allow taxpayers to file a Form 3115 (Application for Change in Accounting Method) and take a Section 481(a) adjustment - a catch-up deduction in the year of change for all previously missed depreciation.

This is generally the correct path when missed depreciation is discovered before a sale. Filing amended returns for each prior year is not required and is often not permitted once the statute of limitations has closed on those years.

Section 280A vacation property: the rental day threshold matters

Under IRC Section 280A(d), a property is treated as a personal residence - not a rental - if personal use exceeds the greater of 14 days or 10% of the days it was rented at fair market value. When personal use crosses that threshold, rental deductions (including depreciation) are limited to rental income; losses cannot be carried forward as passive losses in the normal sense. The basis reduction for allowable depreciation still applies on sale, but the deductible amount during the holding period may have been zero or near zero. Taxpayers who cross the personal-use threshold without realizing it often have both a missed deduction problem and a basis problem waiting at disposition.

Home office depreciation and the sale of a principal residence

Depreciation claimed on a home office reduces the basis allocated to the business portion of the home. On sale, the Section 121 exclusion (up to $250,000 or $500,000 for married filing jointly) does not shelter unrecaptured Section 1250 gain attributable to depreciation taken after May 6, 1997. If a home office was used for several years and depreciation was claimed, a portion of the gain on sale will be taxable regardless of whether the overall gain falls within the Section 121 limit. Taxpayers who skipped home office depreciation to avoid this issue still face basis reduction under the allowed or allowable rule - they get the worst of both outcomes. Readers should confirm current exclusion thresholds and depreciation recovery rules with a tax professional or on IRS.gov, as specific figures and guidance can change.