Mixed-Use and Converted Properties: How Renting Out Your Home Changes What You Owe at Sale

Plenty of people end up owning a property that serves two purposes at once. You rent out the basement, or a spare room, or the back house on your lot. Or the timeline shifts: you buy a rental in Costa Rica intending to move into it once the kids are through college, or you keep the house in Alabama and rent it out while you try Portugal for a few years to see whether it sticks.

Both situations are common, and both are handled well by the tax code - if you understand the rules going in. The problem is that the decisions that matter most get made years before the tax consequences show up. By the time you're selling, the structure of your gain is already locked in. So it's worth understanding the mechanics on the front end, not as a tax professional, but well enough to see what a given plan costs you and whether it's worth it.

Reporting Income on a Mixed-Use Property

Start with the operational side - the annual reporting while you're living in one part of a property and renting out another.

The income side isn't complicated. If you rent out part of your home, that rental income is reportable. Nothing about mixed use changes that.

Deductions are where the work is, and they split into two categories. Direct expenses are the ones tied specifically to the rented portion: painting that space, the washer and dryer you bought for the rental unit, repairs and maintenance that only touch that section. Those are fully deductible against the rental income.

We have a client in Costa Rica who bought an enormous property - around 7,000 square feet - where he and his wife occupy a self-contained portion with its own kitchen, bedrooms and bathrooms. He rents out the entire remaining section. Everything he spends on that side of the house - furniture, upkeep, maintenance - is directly attributable to the rental, and directly deductible.

Indirect expenses are the harder category: mortgage interest, property taxes, insurance, utilities. These affect the whole property, and you can't trace them to one portion. Here you need to allocate using a reasonable method, and square footage is usually both the easiest and the most defensible. Work out the square footage of the rented space against the total, and apply that percentage to your indirect costs.

A rough example. Say you rent out a basement unit that represents 25% of the home's square footage, and it brings in $18,000 a year. You spend $4,000 on expenses tied directly to that space, and your total indirect costs across the property run $32,000, so 25% of that - $8,000 - is allocable to the rental. You're left with $6,000 of net rental income before depreciation.

Depreciation and the Allocation Percentage

Depreciation accounts for wear and tear on the building itself, never the land. The same square footage percentage that governed your indirect expenses also determines how much of the building's basis you can depreciate.

The recovery period depends on where the property sits. Foreign residential rental property uses the alternative depreciation system - ADS - over 30 years, rather than the 27.5-year period that applies domestically. On a property with $300,000 of building basis and a 25% rental allocation, that's $75,000 of depreciable basis producing roughly $2,500 a year. In our example, that brings net rental income down to $3,500, which is what actually lands on the return.

The reverse case is worth understanding too. If the rental side runs at a loss, that loss generally lands in the passive activity bucket rather than offsetting your other income. It gets suspended and carried forward - accumulating year after year until you either generate passive income from the property or dispose of it. Those suspended losses aren't gone; they're waiting. And when you eventually sell, they matter.

Which means the annual lever you're pulling is expense classification. The more legitimately you can push costs into the direct column instead of the allocated indirect column, the lower your reportable rental income each year.

Selling a Mixed-Use Property

Now the sale, where things get more interesting.

Suppose you bought for $400,000, sell for $550,000, and have taken $12,500 of depreciation over the years you rented the basement. Your adjusted basis is $387,500 - the purchase price reduced by depreciation taken. That produces a gain of $162,500.

That gain splits into two pieces, and they're taxed differently. The depreciation you claimed, $12,500, comes back as unrecaptured Section 1250 gain, taxed at a maximum rate of 25% - or your ordinary rate, if it's lower. The logic is straightforward: you took deductions against ordinary income during the rental years, so the government wants that benefit returned when you sell. The remaining $150,000 is long-term capital gain.

Here's the part that surprises people, and it's good news. The Section 121 principal residence exclusion still applies to that capital gain portion. If you've owned and used the property as your principal residence for two of the last five years, you can exclude up to $250,000 of gain filing single, or $500,000 filing jointly. In this example, the full $150,000 of capital gain is wiped out. All you actually pick up is the $12,500 of depreciation recapture, which the exclusion never covers.

The critical condition is that the rented space has to be part of the same dwelling unit you live in. A basement, a spare room, a converted attic - anything under the same roof as your residence - qualifies for the full exclusion with no allocation between business and personal use.

The Separate Dwelling Unit Exception

That changes if the rented space is a genuinely separate structure. A back house, a detached casita, an accessory dwelling unit that you've never personally lived in - that's a distinct property for these purposes, even though it sits on the same lot and sells in the same transaction.

In that case you have to break the sale apart. Allocate your cost basis between the residence and the separate unit, then run two calculations. The residence portion gets the full Section 121 treatment. The separate rental unit gets neither - that gain is long-term capital gain plus depreciation recapture, with no exclusion available.

So the shape of your mixed-use arrangement matters enormously at sale. Renting a room inside your house and renting the cottage behind it look similar day to day, and produce very different results the year you sell.

Converting a Rental Into Your Home

Conversions follow different rules, and this direction is the more complicated of the two.

The scenario comes up constantly: a family vacations in Costa Rica every year, buys a place there, rents it out, and plans to move in once the kids are grown. That plan works - but the gain gets carved up in a way that catches people off guard.

Say you bought for $400,000. Over the rental years you accumulated $30,000 of suspended passive activity losses and claimed $20,000 of depreciation, leaving an adjusted basis of $380,000. You rented for three years, then moved in and lived there for three years, then sold for $550,000. Total gain: $170,000.

You've met the two-out-of-five-year test, so Section 121 is available. But it doesn't apply to all of it. The $20,000 of depreciation is unrecaptured Section 1250 gain, taxable at up to 25% regardless. That leaves $150,000 of capital gain - and this is where the non-qualified use rule bites.

Under Section 121(b)(5), any period after 2008 during which you owned the property but weren't using it as a principal residence is "non-qualified use," and the portion of your gain corresponding to that period can't be excluded. Three years of rental against six years of ownership is 50% non-qualified use. So half your capital gain - $75,000 - is excludable, and the other $75,000 is taxable.

One point worth being precise about, because it's frequently misunderstood: the non-qualified use fraction reduces the gain eligible for exclusion, not the exclusion amount itself. Your $500,000 ceiling stays $500,000. It just has less gain to work against. For most properties that ceiling is generous enough that the distinction never binds, which is why the math still comes out reasonably well.

Then the suspended passive losses come into play. Selling the property is a fully taxable disposition, which releases that $30,000 of accumulated losses and makes them deductible. Net it all out and you're picking up roughly $65,000 - $45,000 of capital gain after the released losses, plus $20,000 of recapture - on an economic gain of $170,000.

Converting Your Home Into a Rental

The other direction is meaningfully better, and the reason is a specific carve-out in the statute.

Non-qualified use does not include any period after the last date you used the property as your principal residence. So rental use that comes after your residence period doesn't count against you at all. Live in the house, move to Portugal, rent it out for a few years, come back and sell - as long as you still satisfy the two-out-of-five-year test, you get the full exclusion with no proration.

Run the same numbers: $550,000 sale, $380,000 adjusted basis, $20,000 of depreciation. The $150,000 of capital gain is fully excluded. You pick up only the $20,000 of recapture. Same property, same dollars, materially different outcome - driven entirely by sequence.

Two Traps Worth Knowing About

The first involves losses. If you own a rental property and sell it at a loss, that's a deductible capital loss you can use against other capital gains. But if you convert that rental into your personal residence and then sell at a loss, the deduction disappears - you're selling a personal-use asset, and personal losses aren't deductible. Moving into an underwater rental before selling it can quietly cost you a real deduction. Worth thinking about before you make the move rather than after.

The second involves basis on the home-to-rental conversion. When you convert a personal residence to rental use, your depreciable basis is the lesser of your adjusted basis or the property's fair market value at the date of conversion. People often assume they can step up to current market value and start depreciating a larger number - if the house appreciated from $400,000 to $750,000, that would mean substantially bigger annual deductions. That isn't allowed. The rule only operates against you: if the property declined to $350,000, you'd be depreciating the lower figure.

Plan It Before You're Selling

The through-line in all of this is recordkeeping. Square footage allocations, direct versus indirect expense classifications, depreciation schedules, suspended loss balances, conversion dates and the fair market value on those dates - all of it needs to be tracked contemporaneously. Reconstructing years of allocation history under audit is a genuinely painful exercise, and the years where the documentation is thinnest are the ones the examiner will focus on.

More importantly, these outcomes are largely determined by decisions you make well before the sale. Whether you rent the basement or the back house. Whether you move into the rental or sell it first. Whether the rental years come before or after your residence years. None of those choices should be made purely for tax reasons, but you should know what each one costs before you commit to it.

If you're renting out part of your home, planning to convert a rental property into a residence, or thinking through the other direction - particularly with foreign property, where the depreciation rules and reporting requirements add another layer - reach out to schedule a consultation. We'll walk through your situation and what it means both for this year's return and for the eventual sale.