I would split the utilities based on square footage of each unit, then add it to the tenant's bill.

Look for properties that have a few bedrooms and large square footage enough to add rooms and ADU.

What is the current market valuation of the property based on comparable sales (defined as similar properties, within a 1-mile radius, within the last 30 to 180 days, that are within 10% of total square footage)? 

McKinney is thriving, but so are other parts of North Texas, and a broader perspective could reveal other great opportunities.Here’s what I’ve observed managing a significant number of rentals in the area:Bedrooms and Layouts:3-bed, 2-bath homes consistently attract the largest pool of tenants and have the highest occupancy rates.4-bedroom homes have grown in demand, especially with the rise of remote work, as tenants look for extra space to use as a home office.Square footage is less critical than number of beds and baths.Supply and Demand:McKinney’s growth is driving demand, but the quality of the location matters greatly.

It's likely they may even use data of SFH with similar lot and building square footage.

Hey Chris, a few thoughts here.Considering that office is not attached to the house, I wouldn’t add any footage to the total home square footage; however, you could advertise that office space and amount of footage and amenities in your remarks.If you’re a Realtor or are using one for the sale, your local MLS may have fields dedicated to additional footage for other buildings on the property, such as ADU’s.The other point is that typically, perhaps depending upon location, a space needs to have heating to count in the square footage, which this office doesn’t have if I understand correctly.Consider contacting an appraiser to inquire about how they would handle this space on an appraisal, or a Realtor.

Start by reviewing the assessment report for errors, such as incorrect square footage or outdated property features.

One property the square footage was high because they assumed both florrs were same size and they were not. 

Quote from @Chris Seveney: Quote from @Devin James: In 2021, we saw buyers upgrading to larger homes, taking advantage of 3% interest rates to afford an extra 300+ square feet.Today, smaller homes are selling much faster as higher rates make additional square footage less affordable.While rates are historically average, I don’t see them dropping significantly.

Square footage is roughly 1600 sqft.Could use minor cosmetic rehab on the outside to make it look pretty, inside is brand new however.