Mixed-Use Cost Segregation: Rental Income, Building Life and Components
By AE Tax Advisors · Published 2026-08-11 · Updated November 8, 2026.
A mixed-use building requires both a building-classification analysis and a component study. Apartments above shops do not automatically justify splitting the whole structure into two depreciation schedules based only on floor area.
Apply the residential-rental test
Under the applicable Section 168 definition, residential rental classification generally depends on whether at least 80% of gross rental income is from dwelling units, with additional rules and exclusions. Review actual leases, receipts and building use rather than substituting an occupancy or square-footage percentage.
Tenant reimbursements and other charges require their proper tax treatment. Relabeling rent as an expense reimbursement does not by itself change the substance or the classification.
Identify buildings and assets separately
Determine what constitutes the relevant building and whether the property includes separate structures. Then identify furnishings, equipment, site improvements and other components using supported classifications. A cost segregation study should explain how it reached those conclusions.
Reconcile the cost allocation
Separate land, acquisition costs, building basis, tenant improvements and assets owned by tenants. Review leases and construction records so an improvement is not included in both the landlord's and tenant's schedules.
Check service dates and deductions
Original acquisition, later buildouts and replacement equipment can have different dates and eligibility. Test bonus and any other expensing provision at the asset level. First-year conventions also affect the building deduction.
Evaluate owner-level use
A correct depreciation schedule does not establish that every loss is currently deductible. Review the ownership entity, basis, at-risk amounts, participation and other limits. State depreciation can require a separate schedule.
Book a Cost Seg Discovery Call with the rent roll, leases, closing allocation, building plans and existing fixed-asset records.
Frequently Asked Questions
Does the percentage of residential floor area decide the 80% test?
Not by itself. The relevant definition uses gross rental income from dwelling units and other applicable rules.
Can a lease label alone change the building’s tax classification?
No. Use the actual tax treatment and substance of the payments.
Sources and review notes
Reviewed November 8, 2026 by AE Tax Advisors. Examples are illustrative; apply the rules to the relevant tax year and records. See our editorial policy.