For 2023 you will have to file a Georgia resident tax return and a California nonresident tax return (assuming that you remain a Georgia resident all year). The gain from the sale of the property in California has to be included in your income on both tax returns. It is subject to California tax because the property is in California, so it is California source income. It is subject to Georgia tax because you were a Georgia resident when you sold it. All of your income is subject to tax by the state that you live in, no matter where the income is from. But you will get a credit on your Georgia tax return for part or all of the tax that you pay to California. The credit will eliminate double taxation.
