AUSTIN (KXAN) — In the City of Austin, more than 10,000 Austin properties advertise themselves as short-term rentals, a new city memo notes. But only 2,500 of those are licensed and paying fees to the city. A number of the unlicensed rentals have been the subject of repeated complaints and violations.

In a memo to the City Council, the Austin Code Department director estimated it will take 35,568 staff hours for license administration and enforcement on short-term rentals in the city by the end of the year. About 5% of staff time is spent on enforcement of the properties that are highlighted by the city as repeat offenders when it comes to breaking Austin’s rules for short-term rentals.

“The department projects that an additional 200 properties will be licensed this year, raising the total number of licensed properties to 2,700—a 59% increase in the number properties licensed over the last two fiscal years. If the total number of STR operations across the City is in fact 10,000+, licensed properties by year end will only represent 27%,” the report said.

There are two parts to the city’s Short Term Rental program: reviewing and approving licenses for units being rented for less than 30 days; and enforcing regulations. The cost of doing that work is estimated to be $2.9 million each year, the city says, and the revenue from the program is also $2.9 million per year.

So far this year, investigators have found code violations on 581 short-term rental properties — 543 of which are unlicensed. The Austin Code Department also noted 36 properties had four or more enforcement actions taken against them.

The city is using a third-party, Host, to identify information about unlicensed properties. It is working to get location and advertising information on 3,500 unlicensed properties to the city by February 2020. The Austin Code Department reports it’s already issued 224 notices of violation for illegal advertising using Host’s data.

The city memo came after Mayor Pro Tem Kathy Tovo brought a resolution last November asking the Austin Code Department to quantify how much time enforcing short-term rentals is taking and whether the city needs to do more to hold problem property owners accountable.

Austin has been contending with the rise of short-term rentals for years. While it does have an ordinance regulating companies like Airbnb and Homeaway, it may be re-evaluating how it taxes them. The city is also on-track to phase out certain types of short-term rentals by the year 2022.