The short version
- Some cities allow only one short-term rental in a duplex when the owner doesn't live there. Saint Paul, Minnesota is one example.
- A stay of 30 nights or more often falls outside those rules, so the second unit can still earn as a furnished monthly rental.
- The monthly unit smooths your income: one guest, one cleaning, fewer messages.
- Read your own city's rules and get a signed written agreement for every 30-night stay.
The one-per-building rule
Many cities that allow short-term rentals limit how many can run in one building. A common version: if the owner lives on site, every unit can be a short-term rental. If the owner lives somewhere else, only one can.
For a host with a duplex, that rule decides whether the building earns like two rentals or one.
One city's rules: Saint Paul
Saint Paul, Minnesota publishes its limits in a table. These rows are taken from the city's short-term rental page:
| Property type | Short-term rental units allowed |
|---|---|
| Single-family, owner lives there | 1 |
| Single-family, owner doesn't live there | 1 |
| Duplex, owner lives in either unit | 2 |
| Duplex, owner lives in neither unit | 1 |
| Triplex, owner lives in one unit | 3 |
| Triplex, owner lives in none | 1 |
The city also defines a short-term rental as a stay of less than 30 days, and every short-term unit needs its own license, renewed each year. A duplex whose owner lives elsewhere gets one licensed short-term unit. The other unit can't take stays of less than 30 days.
The play: two kinds of stay
Run the licensed unit as a normal short-term rental. Furnish the second unit the same way, and rent it only for stays of 30 nights or more.
- Upstairs (licensed): weekend visitors, families in town for an event, short work trips.
- Downstairs (30 nights or more): travel nurses, people between homes, someone in the middle of a divorce, a family whose house is being repaired.
The two kinds of guest rarely compete. The short-stay guest finds you on a booking platform. The monthly guest usually comes through a partner or a furnished-rental site, and the transition housing playbook covers how to reach them.
Why the second unit matters
One short-term unit has a ceiling: its nightly rate times the nights in a month. With an example rate of $150 a night, a fully booked 30-night month tops out at $4,500, and no unit is fully booked every month.
A second unit on a monthly stay adds a separate line of income. It needs one cleaning, one check-in and far fewer messages. In a slow month for short stays, the monthly guest keeps paying.
These figures are an example, not a forecast. Put in your own rate and your own local monthly rent before you decide.
What to check in your city
- How your city defines a short-term rental. Many use “less than 30 days”, some use a different number of nights.
- How many short-term units your building type allows, and whether living on site changes it.
- Whether monthly furnished rentals need their own license or a rental registration.
- Tax on 30-night stays. In Minnesota, a stay of 30 days or more avoids lodging sales tax only with an enforceable written agreement signed on or before day one, with a 30-day termination clause.
- Your insurance, for both kinds of guest.
Before you list: city rules change. The Saint Paul figures above come from the city's page as last edited on October 3, 2023. Confirm them with the city, and treat nothing here as legal or tax advice.
Questions hosts ask
Does a 30-night stay count as a short-term rental?
In Saint Paul, no. The city defines a short-term rental as a stay of less than 30 days. Other cities draw the line at 30 days too, but not all of them, so read your own city's definition.
Where do I find 30-night guests?
Referral partners send the best ones: attorneys and mediators for people in a divorce, realtors for people between homes, insurance adjusters for families whose home is being repaired. Furnished-rental sites that list monthly stays help too.
Can I switch the units around later?
Usually, as long as the licensed unit stays the licensed one or you update the license. Ask your city before you move the short-term listing to the other unit.
Want us to look at your setup?
20 minutes on a call. We look at your PMS, your guests and your gaps, then tell you plainly whether Book Them Twice fits.
Sources
- City of Saint Paul, Short Term Rentals (units allowed by property type; last edited October 3, 2023)
- City of Saint Paul, Short Term Rental Host and Platform License (“short term means a period of less than 30 days”)
- Minnesota Department of Revenue, “Sales – Lodging and Related Services” (the 30-day written agreement rule)
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