Sq. foot on tax records is HALF of actual-will I owe back taxes?

[Ben Hendricks]

So I found what I think could be a really good deal, and has been overlooked by other investors because the square footage is so low. The house is listed on tax record are around 800 square feet--tiny! But after visiting the property in person, I quickly realized that was way off--there is an addition that nearly doubled the size of the house, so now are are closer to 1400-1500 square feet. The addition appears to be fairly old, but well built--the original house is mid 1950's, and the addition, by my best guess, was probably added in mid 70's. The house has changed ownership a handful of times also since the addition would have been added, so apparently other owners wanted to fly under the rader here with the lower sq foot number. So here's my question--If I purchase this property, what are the property tax implications? The area is appreciating steadily and becoming revitalized, so I think my exit plan would be to sell in 2-3 years. Of course when I do sell, I'd love to have it listed at the correct square footage, but would there be any type of back taxes owed since the assessed value has been off the 800sq foot number? For additional context, I'm in the state of Georgia. I know county-by-county may have different rules and a lawyer/CPA may need to weigh in, but I'd love any and all advice, thoughts, etc! Thanks all!