Multi-Family Property Taxes: Duplex, Triplex & Fourplex Guide
Owning a 2-4 unit property — especially one you live in — creates unique tax situations. You get rental deductions on the investment units while claiming homeowner benefits on yours. Here's how to handle the allocation correctly.
In This Guide
1. Owner-Occupied Multi-Family Advantages
Living in one unit of a 2-4 unit property gives you the best of both worlds — homeowner tax benefits on your unit and investor tax benefits on the rental units:
Your Unit (Personal)
- - Mortgage interest deduction (Schedule A)
- - Property tax deduction (Schedule A, up to $10K SALT cap)
- - Section 121 exclusion when you sell ($250K/$500K)
- - FHA/VA low-down-payment financing
Rental Units (Investment)
- - Depreciation deductions (27.5 years)
- - All operating expenses deductible
- - Mortgage interest deduction (no $750K cap)
- - Property tax (no SALT cap on rental portion)
- - $25K loss allowance against other income
Key Benefit: Mortgage interest on the rental portion has NO cap. The $750,000 mortgage limit only applies to your personal residence portion. On a $600K fourplex where you live in one unit, only 25% (your unit's $150K share) counts toward the $750K limit. The other 75% ($450K) is fully deductible on Schedule E with no limit.
2. How to Allocate Costs Between Units
When you live in one unit and rent the others, you must allocate shared expenses between personal and rental use. The most common (and IRS-accepted) methods:
| Method | How It Works | Best For |
|---|---|---|
| Number of units | Duplex = 50% rental. Triplex = 66.7%. Fourplex = 75%. | Equal-sized units |
| Square footage | Rental sqft ÷ total sqft = rental percentage | Unequal unit sizes (most accurate) |
| Rooms | Number of rental rooms ÷ total rooms | Rooming houses |
Example: Owner-Occupied Triplex
Unit A (yours): 1,100 sqft
Unit B (rental): 900 sqft
Unit C (rental): 900 sqft
Total: 2,900 sqft
Rental percentage: (900 + 900) ÷ 2,900 = 62.1%
Annual mortgage interest of $18,000:
→ Schedule E (rental): $18,000 × 62.1% = $11,178
→ Schedule A (personal): $18,000 × 37.9% = $6,822
3. Depreciation for Multi-Family
You can ONLY depreciate the rental portion of the property. Your personal unit is not depreciable (just like any primary residence).
Depreciation Example: Fourplex ($400K, 25% Land)
Purchase price: $400,000
Land value (25%): $100,000 (not depreciable)
Building value: $300,000
Rental portion (3 of 4 units): 75%
Depreciable basis: $300,000 × 75% = $225,000
Annual depreciation: $225,000 ÷ 27.5 = $8,182/year
Component Depreciation
Items that serve only the rental units depreciate at 100% rental allocation. Shared items (roof, foundation, shared HVAC) use your rental percentage.
- Rental-only appliances: 100% depreciable over 5 years (stove, fridge, washer/dryer in rental units)
- Shared roof replacement: Rental percentage × cost ÷ 27.5 years
- Shared HVAC: If one system serves all units, allocate by rental percentage
- Unit-specific improvements: 100% to that unit (e.g., new bathroom in Unit B = 100% rental depreciation)
4. Shared vs. Unit-Specific Expenses
The allocation rules depend on whether an expense benefits all units or specific units:
100% Deductible on Schedule E (Rental-Only)
- - Repairs to rental units only
- - Appliances purchased for rental units
- - Advertising for vacant rental units
- - Tenant screening costs
- - Turnover cleaning and painting for rental units
Allocated by Rental Percentage (Shared)
- - Mortgage interest and property taxes
- - Insurance premium (entire building)
- - Roof, foundation, exterior painting
- - Shared utilities (water, trash, common area electric)
- - Landscaping, snow removal, pest control
- - HOA fees (if applicable)
NOT Deductible (Personal Unit Only)
- - Repairs only to your personal unit
- - Furnishings for your unit
- - Utilities for your unit only (your electric meter)
5. Selling: Capital Gains & Section 121
When you sell an owner-occupied multi-family, you get split tax treatment:
Your Unit: Section 121 Exclusion
Exclude up to $250,000 ($500,000 MFJ) of gain on your personal unit if you lived there 2+ of the last 5 years. No depreciation recapture since your unit wasn't depreciated.
Rental Units: Standard Investment Treatment
Capital gains tax (15-20%) on appreciation + 25% depreciation recapture on all depreciation taken. Consider a partial 1031 exchange on the rental portion only.
Example: Selling Duplex (Lived in Unit A, Rented Unit B)
Purchase: $300K (50/50 split = $150K each unit)
Sale: $500K (50/50 = $250K each unit)
Unit A gain: $100K → Excluded under Section 121 (tax-free)
Unit B gain: $100K → Taxed at capital gains rates
Unit B depreciation recapture: ~$38K → Taxed at 25%
Net: You pay tax on Unit B only. Unit A is completely tax-free.
6. House Hacking Tax Benefits
"House hacking" — living in one unit and renting the others — offers exceptional tax benefits beyond what pure investors or pure homeowners get:
FHA 3.5% Down Payment
You can buy a fourplex with just 3.5% down ($14,000 on a $400K property) because it's your primary residence. Pure investors need 20-25% down.
Rental Income Qualifies for the Mortgage
Lenders count 75% of projected rental income toward your DTI ratio, letting you qualify for a larger loan than a single-family home.
Live-In Flip Potential
Live there 2 years, build equity, sell with Section 121 exclusion on your unit, and 1031 exchange the rental portion into a larger property.
Effective Housing Cost Near $0
Three rental units at $1,500 each = $4,500/mo. If your mortgage is $3,200/mo, tenants cover your housing AND generate $1,300 cash flow.
7. How SheltrIQ Handles Multi-Family
Multi-family properties with mixed personal/rental use require careful expense allocation. SheltrIQ handles this automatically:
Unit-Level Tracking
Tag income and expenses to specific units. Shared costs are auto-allocated by your chosen method (sqft, units, or custom).
Split Depreciation
Calculates depreciation only on the rental portion, handling unit-specific assets vs. shared building components.
Personal/Rental Split
Generates separate reports for Schedule A (personal) and Schedule E (rental) from the same property.
Sale Modeling
Models Section 121 exclusion on your unit + capital gains/recapture on rental units for accurate sale planning.