Thanks Thomas — Sorry, I left out a nuance that turned out to be key. The following is completely separate from the office use percentage.
Although I paid property taxes the whole year, I had a home office for only the last few months of year. So, when it came time to enter the property taxes related my home office, I only inserted the amount of property taxes that I paid across that last-few-months period, rather than my actual total paid for the entire year. Continuing the example from my original post, I had put $1,000 (out of my total $5,000 in property taxes) into this field: "If [name] paid real estate (property) taxes on the entire home, enter this amount here and later go to the Deductions & Credits area and review the property tax information."
So now, arriving in the Deductions & Credits section, it says (continuing my example from my post), "Don't enter your home office deduction, $1,000 is already included. You can change this." And then the field "Property taxes on your main home" is pre-populated with the $1,000.
(Side note related to your response: Although the actual amount deductible for the home office would've only been a percentage of that $1,000, you can see that TurboTax ported over the entire $1,000 into the "Property taxes on your main home" field.)
As you can see, TurboTax appears to have populated $1,000 as if that was my full reported property tax from earlier (it did NOT port over just a smaller percentage). So does that mean I now replace it with the full total $5,000 into this Deductions & Credits section? But if that's what I'm supposed to do, why is it saying "$1,000 is already included"?
