House Hacking Tax Rules (2026 Guide)

House hacking, living in one unit of a small multifamily while renting the others, or renting rooms in a single family home, creates a property that is partly a residence and partly a rental. The tax code handles this by splitting it.

The split determines your depreciation, your deductions, your capital gain exclusion at sale, and whether a cost segregation study is worth running. Most house hackers do the allocation casually and lose real money on both ends.

How the Allocation Works

You must allocate the property between personal use and rental use on a reasonable basis. For a duplex where you occupy one unit and rent the other, square footage is the standard method and is generally the cleanest.

For a single family home with rented bedrooms, the allocation is more nuanced. The rented bedrooms are clearly rental. Shared common areas, the kitchen, living room, and hallways, are commonly allocated between personal and rental use based on the ratio of exclusive space or on occupancy. Both approaches have support. What matters is choosing a defensible method and applying it consistently year over year.

The allocation percentage drives everything downstream. Depreciation applies only to the rental portion of the building. Mortgage interest and property taxes split, with the rental share deducted on Schedule E and the personal share deducted on Schedule A subject to the SALT cap and mortgage interest limitations. Utilities, insurance, and repairs affecting the whole property split by the same percentage. Repairs affecting only the rental portion are fully deductible against rental income.

Depreciation on the Rental Portion

The rental portion of the building is depreciated over 27.5 years as residential rental property under IRC Sec. 168(e)(2)(A). Land is not depreciable, so the purchase price must first be split between land and building, then the building split between personal and rental use.

On a $520,000 duplex with $95,000 of land value, the depreciable building is $425,000. At a 50% rental allocation, depreciable basis for the rental is $212,500, producing $7,727 of annual depreciation.

Furniture and appliances placed in the rental unit are separately depreciable as five-year property, fully deductible in the placed-in-service year under IRC Sec. 168(k). For a furnished unit, this is a meaningful first-year item that house hackers routinely miss.

Cost Segregation on the Rental Share

A cost segregation study applies to the rental portion. On a duplex with 50% rental allocation and $212,500 of rental depreciable basis, a study reclassifying 24% produces roughly $51,000 of first-year deduction.

Whether that is worth the study cost depends on the property value and on whether the loss is usable. For a $500,000 duplex, the arithmetic is marginal. For a fourplex where the investor occupies one unit and rents three, with $700,000 of rental basis, it is clearly worth running.

The usability question is the same as for any rental. Under IRC Sec. 469 the loss is passive unless you qualify as a real estate professional. The $25,000 special allowance under IRC Sec. 469(i) is available to active participants with modified adjusted gross income under $100,000, phasing out completely at $150,000. Many house hackers are early in their careers and actually fall within this range, which makes the allowance more relevant here than in most rental contexts.

The Section 121 Exclusion at Sale

This is where house hacking gets genuinely favorable. Under IRC Sec. 121, you may exclude up to $250,000 of gain, $500,000 for married filing jointly, on the sale of a principal residence owned and used as such for two of the preceding five years.

For a house hack, the exclusion applies to the personal use portion. The rental portion's gain is not excluded, and depreciation claimed after May 6, 1997, is recaptured as unrecaptured Sec. 1250 gain at up to 25% regardless of the exclusion.

There is an important distinction between separate dwelling units and rented space within one dwelling unit. Where the rental is a separate unit in a duplex, the allocation applies and only the residence portion qualifies. Where you rented bedrooms within the same dwelling unit you occupied, the regulations under Treasury Regulation Sec. 1.121-1(e) generally do not require allocation for the non-residence use within the dwelling unit, though depreciation recapture still applies. This distinction is worth understanding before choosing a house hacking structure.

Worked Example: Fourplex House Hack

An investor buys a fourplex for $760,000, occupies one unit, and rents three. Land is allocated at $140,000, leaving $620,000 of building. The rental allocation by square footage is 74%, giving $458,800 of rental depreciable basis.

A cost segregation study reclassifies 25% of the rental basis, producing $114,700 of five-year and 15-year property deductible in year one under IRC Sec. 168(k), plus roughly $12,500 of structural depreciation. First-year depreciation on the rental portion is approximately $127,200.

The investor's modified adjusted gross income is $128,000, so the $25,000 special allowance under IRC Sec. 469(i) is partially phased out, allowing $11,000 of the loss currently. The balance suspends and carries forward.

Three years later the investor moves out, converts the fourth unit to a rental, and the property becomes fully rental. The suspended losses remain available and release against future passive income or on a fully taxable sale.

Converting Fully to a Rental Later

Most house hackers eventually move out. On conversion, the former personal use portion becomes rental property, and depreciation begins on it.

The basis for depreciation on the converted portion is the lesser of adjusted basis or fair market value at the date of conversion, under Treasury Regulation Sec. 1.168(i)-4. In an appreciating market this generally means your original cost basis, which is lower than value, so appreciation does not increase your depreciation.

Timing matters for the Sec. 121 exclusion. You must have used the property as a principal residence for two of the five years before sale. An investor who moves out and rents for more than three years loses the exclusion on the residence portion entirely. For a house hacker with substantial appreciation in the personal use share, selling within that window, or executing a 1031 exchange on the rental portion while excluding the residence portion, can be worth six figures.

Frequently Asked Questions

How do I split expenses between personal and rental use?

On any reasonable basis, applied consistently. Square footage is standard for separate units in a duplex or fourplex. For rented rooms in a single family home, allocation based on exclusive space or occupancy both have support. Choose a method, document it, and apply it the same way every year.

Can I depreciate a house hack?

Yes, on the rental portion only. Split the purchase price between land and building, then apply your rental use percentage to the building. Furniture and appliances placed in the rental space are separately depreciable as five-year property and fully deductible in year one.

Is a cost segregation study worth it on a house hack?

It depends on the rental basis. On a duplex with roughly $200,000 of rental basis, the arithmetic is marginal. On a fourplex with $450,000 or more of rental basis, it usually is worth running, provided you can actually use the resulting loss.

Do I lose my capital gains exclusion by renting part of my home?

Partly. The IRC Sec. 121 exclusion applies to the residence portion. Gain on a separate rental unit is not excluded, and depreciation claimed after May 6, 1997, is recaptured at up to 25% regardless. Renting rooms within your own dwelling unit is treated more favorably than renting a separate unit.

Can I use house hacking losses against my W2 income?

Possibly, through the $25,000 special allowance under IRC Sec. 469(i) for active participants. It phases out between $100,000 and $150,000 of modified adjusted gross income. Many house hackers are early enough in their careers to fall within the range, which is unusual among rental owners.

House Hacking Tax Rules: Allocating Between Personal Residence and Rental