For US tax law, you may owe capital gains tax when you sell property for more than you paid.
In the case of a personal home, you can exclude (not count as income) up to $250,000 of capital gains when you sell your personal home, as long as you used it as your main home for at least 2 of the past 5 years and owned it at least 2 years. In the case of divorce, the spouse who moves out of the home still qualifies for the exclusion as long as the other spouse stayed in the home and also qualifies for the exclusion. However, there are special rules if the home was ever used as a rental or for business (like a home office).
First, we need to know what the capital gain actually was. Thats the difference between the selling price and the adjusted cost basis. The adjusted cost basis is the purchase price, plus certain closing costs, plus the cost of any permanent improvements (but not repairs or maintenance). See IRS publication 523. https://www.irs.gov/pub/irs-pdf/p523.pdf Capital gains is not related to the actual sales proceeds. For example, suppose the home was bought for $100,000, and sold for $200,000. But the proceeds were only $50,000 because a few years, ago, you refinanced for $150,000 and used the cash for other purposes. Your gain is $100,000 because that's the difference between purchase and selling price. You only got half the gain when you sold the home because you cashed out the other half of the gain when you refinanced.
Second, we need to know if the home was ever used as a home office or a rental.
Third, we need to know if your spouse lived in the home for at least 2 year (730 days) out of the past 5 years. The days do not have to be consecutive.
If you want to see an accountant for advice, they will need to know the answers to those questions.
If we assume the home was never used in business, and your spouse does meet the use test, then you can exclude (not count as taxable income) the first $250,000 of your capital gains. If your gains are larger than that, they will be taxed at 15%, or 20% if your total income including the gain is more than about $450,000. You will also pay state income tax on your gains, state tax rates vary from 3%-13% depending on the state and your income.
Lastly, note that if your gain is taxable, and you moved out of the state where the home is located, you may have to file a non-resident return for that state, because the sale of a home is considered in-state income. For example, suppose the home is located in California but you have moved to Arizona, and the total gain was $600,000. Your half is $300,000, which means $50,000 is taxable. You will have to report that as CA income on a CA non-resident tax return. The income is also included on your home state tax return because you pay tax on all your world-wide income to your home state. But your home state will give you an offsetting credit for taxes paid in another state on the same dollars.
