Multi Family Tax write offs?

Question

Hi there I am looking to invest in my first property and thinking of a duplex or triplex, one of my advisors said to learn how the taxes would work if

1. I happen to live in one of the units (house hack)

What can I write off as a "investment property"? or can I write it off as as a investment property if I live in one of the units? or do I need to rent out all the units in order to do that?

Also can I write off the purchasing the property as a tax write off if I live in one of the units or do I need to rent all the units out?

Also if there is any advice you can share related to tax write offs for purchasing a multi family I would be very grateful for that as well. Thanks!

Julius Vincent · Answer

Hey @Dennis Kim - Building on Michael’s solid answer, think of a house hack as two properties in one:

- Your personal unit: treated like a primary residence. Your share of mortgage interest and property taxes only show up as itemized deductions on Schedule A (if you itemize). If you take the standard deduction, you won’t see a benefit here. Personal expenses like utilities for your own unit aren’t deductible.

- The rental units: full rental deductions on Schedule E. Shared costs (like insurance, roof repairs, etc.) get split by square footage or units, while direct costs tied to a rental unit are 100% deductible. You also get depreciation on just the rental portion of the building, not the part you live in.

Bill Hampton · Answer

Dennis, I recommend that you hire a tax accountant that specializes in real estate taxation. Your property will be part rental and part personal residence. Your tax accountant will explain what is deductible.

There are plenty of tax accountants on here that specialize in real estate taxation. Reach out to a few and see who you like.

Good luck.

Mose Gebremeskel · Answer

Good questions. This trips up a lot of first-time house hackers. The short version is: you can only write off the portion of the property that’s used as a rental. If you buy a duplex and live in one unit, you can generally deduct expenses tied to the other unit (repairs, insurance, depreciation, etc.). Things like property taxes and mortgage interest usually get split between your personal side and the rental side based on square footage.

You don’t get to write off the actual purchase price as an expense, but you can depreciate the rental portion of the building over time. That’s where a lot of the tax benefit comes from. My team just had a great conversation with KC Chohan, a real estate tax strategist, on our podcast about this exact topic, how to maximize deductions and use tax loopholes legally. Might be worth a listen if you’re starting out with a duplex/triplex and want to get the strategy side right from the jump: https://linktr.ee/rentishpod

Basit Siddiqi · Answer

If you house-hack, which is buying a property where you will live in and also have renters, you have both a personal residence and an investment property.Therefore, you have to split costs as personal deductions and rental deductions. This is normally done by allocating costs based on square footage or amount of bedrooms.Best of luck!

Ashish Acharya · Answer

The biggest difference between your options comes down to how much depreciation and deductible interest you can create, and whether you can actually use those deductions based on your investor status. The duplex conversion is cleaner and lower risk, but the ADU conversion offers more tax play if you’re comfortable with the leverage and paperwork. On the other hand, the Airbnb option at your primary home may give you more flexibility with less financial stretch.

Key Tax Points to Consider:

• Depreciation:Duplex only → About $15k/year straight-line depreciation.ADU conversion → Extra $50–60k basis added, with potential for cost segregation and bonus depreciation (front-load tax savings).Airbnb conversion → Similar depreciation benefits, possibly even more advantageous if treated as a short-term rental.
• Duplex only → About $15k/year straight-line depreciation.
• ADU conversion → Extra $50–60k basis added, with potential for cost segregation and bonus depreciation (front-load tax savings).
• Airbnb conversion → Similar depreciation benefits, possibly even more advantageous if treated as a short-term rental.
• Interest Deductions:HELOC interest is deductible as long as the funds are traced to the rental/rehab.If used for personal expenses or non-rental projects, it’s not deductible.
• HELOC interest is deductible as long as the funds are traced to the rental/rehab.
• If used for personal expenses or non-rental projects, it’s not deductible.
• Classification:Duplex/ADU → Generally Schedule E (passive activity limits apply unless you qualify as a Real Estate Professional).Airbnb → Could fall under Schedule E if you DO NOT provide significant services (no passive loss restrictions, but may trigger self-employment tax).
• Duplex/ADU → Generally Schedule E (passive activity limits apply unless you qualify as a Real Estate Professional).
• Airbnb → Could fall under Schedule E if you DO NOT provide significant services (no passive loss restrictions, but may trigger self-employment tax).
• Risk vs. Cushion:Duplex only = safer, steady tax deductions.ADU = more upside, more tax shields, but riskier with liquidity and refinance uncertainty.Airbnb = less leverage, faster after-tax cash flow, but depends on STR regulations and management.
• Duplex only = safer, steady tax deductions.
• ADU = more upside, more tax shields, but riskier with liquidity and refinance uncertainty.
• Airbnb = less leverage, faster after-tax cash flow, but depends on STR regulations and management.

• Duplex only → About $15k/year straight-line depreciation.
• ADU conversion → Extra $50–60k basis added, with potential for cost segregation and bonus depreciation (front-load tax savings).
• Airbnb conversion → Similar depreciation benefits, possibly even more advantageous if treated as a short-term rental.

• HELOC interest is deductible as long as the funds are traced to the rental/rehab.
• If used for personal expenses or non-rental projects, it’s not deductible.

• Duplex/ADU → Generally Schedule E (passive activity limits apply unless you qualify as a Real Estate Professional).
• Airbnb → Could fall under Schedule E if you DO NOT provide significant services (no passive loss restrictions, but may trigger self-employment tax).

• Duplex only = safer, steady tax deductions.
• ADU = more upside, more tax shields, but riskier with liquidity and refinance uncertainty.
• Airbnb = less leverage, faster after-tax cash flow, but depends on STR regulations and management.

If cash is tight, the home Airbnb conversion may actually give you the best balance of tax benefits and financial safety. It avoids stretching your HELOC thin while still delivering depreciation and deductible expenses you can actually use. If you want to pursue the ADU BRRRR, make sure you line up cost segregation and properly document HELOC use so every dollar of interest is deductible. The duplex-only option is the simplest, but probably the weakest tax play compared to the other two.

This post does not create a CPA-Client relationship. The information contained in this post is not to be relied upon. Readers should seek professional advice.

Bryan Martin · Answer

If you house hack:

• Your unit = personal (no rental write-offs).
• 
• Tenant units = rental. You can deduct their share of mortgage interest, taxes, insurance, repairs, utilities, and depreciate the rental portion.
• 
• Shared costs (roof, lawn, etc.) get split.
• 
• You can’t deduct the purchase price, only depreciate the rental share of the building.
• 
• Sell later: rental side faces depreciation recapture; your side may qualify for the $250k/$500k home sale exclusion.

Keep records clean—treat rental and personal separately

Jason Malabute · Answer

For tax purposes, when you live in one unit and rent out another, it’s really treated as if you own two separate properties: one personal and one rental. The personal side is handled like a primary residence, meaning your share of mortgage interest and property taxes can only be deducted if you itemize on Schedule A, and if you take the standard deduction, you likely won’t see a benefit. Personal expenses like your own utilities aren’t deductible. The rental side is reported on Schedule E, where you can deduct all the expenses tied to that unit. Shared expenses such as insurance or roof repairs are usually divided based on square footage or number of units, while costs that only apply to the rental are fully deductible. You’re also able to take depreciation on the rental portion of the property, but not on the part you live in.

Aaron Zimmerman · Answer

When you purchase a house hack, you will want to figure out the split between rental (deductible) and personal. The way to do this is by looking at the number of bedrooms or square footage, whichever is most advantageous.

example: you have 10 total bedrooms. You occupy 2. Common expenses such as mortgage interest, insurance, taxes, etc are 80% deductible expenses against rental income. The remaining 20% are non-deductible except taxes and interest (which may be itemized on schedule A)

Rohullah Sharifi · Answer

Congratulations on your new investment!

To take full advantage of the tax benefits, you’ll need to either actively participate in the rental activity or consider a Short-Term Rental (STR) strategy, which can potentially reclassify your income as non-passive if certain criteria are met.

I also recommend maintaining detailed and accurate accounting records from the start — this includes tracking income, expenses, and any personal vs. rental use — as this will be essential for proper tax reporting and maximizing deductions.

Let me know if you'd like help.

Michael Plaks · Answer

The first thing to understand is that, for tax purposes, you will have two properties, not one: the unit where you live which is personal and the rental part of the property which is business.

Tax deductions for the business portion will work almost exactly the same as if it was a separate building.

The exact way rental property taxes work is impossible to describe in one post. For example, you don't write off purchasing the property immediately, you do it slowly over multiple years through depreciation. Depreciation is explained here: https://www.biggerpockets.com/forums/51/topics/1121063-expla...

Multi Family Tax write offs?

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