A casita can pay for itself, but it depends on four things: what the build costs, the nightly rate and occupancy you can actually hold, the roughly 13% lodging tax that comes off the top, and the local rules that, in some places, can block short-term renting entirely. Get all four right and the math works. Miss one and it does not.
How does a casita earn rental income?
Short-term rental revenue is just nightly rate times occupancy, then minus everything else. For directional context, AirDNA reports the Austin metro running near 54% occupancy at about a $265 average daily rate (AirDNA, 2026). That is vendor data for Austin, not Wimberley, so treat it as a ballpark only, not a promise of what your guest house will earn out here.
Run your own honest numbers before you build. Take a realistic nightly rate, multiply by the nights you expect to book in a year, and you have gross revenue. Then start subtracting. The gap between that gross figure and what lands in your pocket is wider than most owners expect, and the rest of this post walks through where the money goes.
What comes off the top of rental revenue?
Lodging taxes alone take roughly 13% before you count a single other expense. A Wimberley short-term rental collects a 7% city hotel occupancy tax on top of the 6% Texas state hotel occupancy tax (City of Wimberley; Texas Comptroller, current). The state tax applies to stays under 30 days, so a long-term tenant is taxed differently than a weekend guest.
After tax, the real costs begin. Cleaning between guests, listing-platform fees, supplies, utilities, insurance, repairs, and property management if you hire it all eat into the gross. Many owners hand the day-to-day to a management company and pay for that convenience. We build the casita; we do not manage rentals, so plug in real local quotes for those line items rather than guessing.
One cost owners routinely underestimate is insurance. A standard homeowner’s policy usually will not cover a unit you rent out to guests, so you need a short-term rental or commercial policy, and that costs more than the coverage you carry today. Build it into your numbers from the start, because finding out a claim is denied after a guest gets hurt is the worst possible time to learn the policy did not apply.
Here is the honest framing. Start with gross revenue, subtract about 13% in lodging tax, subtract management and cleaning and operating costs, and what remains has to service the build cost before you call it profit. That is the test of whether a casita pays for itself, and it is worth doing on paper first.
Can you even short-term rent a casita in Wimberley?
Maybe, and that word matters. The City of Wimberley requires every short-term rental to hold a Conditional Use Permit approved by City Council, with separate categories for owner-on-site versus owner-off-site rentals (City of Wimberley, current). The city has also had a temporary moratorium on new permit applications, so do not assume you can get one today.
Confirm the current status with the city before you count on a single night of rental income. Rules change, moratoriums lift and return, and a permit is never guaranteed. Texas has no clean statewide rule forcing cities to allow short-term rentals, so local ordinance controls (Texas Legislature, 2023 to 2026). On acreage governed by an HOA, a generic “residential use” covenant alone usually does not ban renting, per the Texas Supreme Court in Tarr v. Timberwood Park (Supreme Court of Texas, 2018). That ruling covered HOA covenants only, not city or county authority. For permit questions, talk to the city, not to us.
Why does septic decide so much in Hays County?
Out here, septic capacity is often the quiet dealbreaker. In unincorporated Hays County, any residential structure must connect to a permitted on-site sewage facility, and a new casita generally triggers a septic review or upgrade (Hays County, current). This is the construction reality we know firsthand from building guest houses across the Hill Country.
The state sizes septic by bedrooms, not by square feet. Under TCEQ rules, a three-bedroom home is designed around roughly 300 gallons per day, or about 240 with water-saving fixtures, and adding a casita bedroom raises that design flow (TCEQ, current). Push past what your existing system handles and you may need a larger field or a second system entirely. That cost can swing a project, so we check septic capacity early when we plan a casita. Getting the system right is also what makes a unit genuinely rentable-ready, alongside a separate entrance and its own parking.
What does a casita actually cost to build?
Expect to pay more per square foot than a full house, not less. NAHB pegged 2024 custom-home construction at a median of $166 per square foot nationally, and about $138 across the West South Central region that includes Texas (NAHB, 2024). A small casita still needs a full kitchen, a bathroom, and utility hookups, so those fixed costs spread over fewer square feet push the per-foot number higher.
National estimators put detached stick-built accessory units in a wide range, often $150 to $300 per square foot (Angi, 2026). In our experience building here, the Hill Country adds its own line items: limestone and caliche soils, sloped lots, and the septic work above. We give you a real number for your lot and your plan rather than a national average, because the site drives the cost as much as the floor plan does.
What about financing and property tax?
Recent mortgage rules have started to recognize rental income from an accessory unit. As of 2026, Fannie Mae allows ADU rental income on a one-unit principal residence to count toward qualifying income, capped at 30% of total qualifying income, with the appraisal supported by Form 1007 (Fannie Mae, 2026). This policy is recent, so verify it still applies and ask your lender how it works for your loan.
Property tax is its own conversation. The Texas school-district homestead exemption and the 10% appraisal cap apply to your residence, not to business use, and how an appraisal district treats a rented casita is decided case by case (Texas Comptroller, 2026). Take those questions to Hays CAD, and take income-tax questions to your CPA. We are the builder, not your tax or legal adviser.
So can a casita pay for itself?
It can, with the right lot, a real budget, bookings that hold, and a permit you can actually get. The honest answer is that it depends, and any one of these factors can sink the math. Septic and build cost are construction facts we can pin down for you today. The rental rules and tax treatment shift, so confirm them with the city, Hays CAD, and your CPA before you commit.
If you want a casita that is built right and rentable-ready, with septic capacity, a separate entrance, and parking planned from day one, Iron C Construction has built guest houses and casitas across the Wimberley area and the wider Hill Country since 2020. Reach out and we will walk your lot, talk through real costs, and give you straight answers before you spend a dollar.
