Investors & landlords

You are in a situation where you have "non-qualified use."  This is not well explained in the IRS publications but it is included in worksheet 2 of publication 523.  https://www.irs.gov/forms-pubs/about-publication-523

Also, you must recapture the depreciation you could have taken, even if you didn't.  You may want to see an accountant.  There may be a way to correct some of that depreciation and get a tax break for it now.  

To try and make this short, you can't convert a taxable gain on a rental into an exclusion by moving back into the home.  The in between period is non-qualified use.  In your case, suppose you move back in 6/23 and sell in 6/25.  You will be allowed to use the 5 year rule, but you have to account for the period of non-qualified use.  At that point, you would have 3.5 years of qualified use from 2012-2016 and 2 years of qualified use from 2023-2025, and 7.25 years of non-qualified use.  Of the total 12.75 years of ownership, 5.5 years, or 43%, is qualified.  Suppose your gain is $600,000, and $50,000 is attributable to depreciation you could have taken.   You pay ordinary income tax on the $50,000 depreciation recapture with a maximum of 25%.   Then, you pay long term capital gains tax on the non-qualified gain (57% of $550,000, or $313,500) The remaining qualified gain (47%, or $258,500) is eligible for the exclusion under the 2 year/5 year rule.  The longer you live in the house, the higher your qualified percentage, but you will never be able to exclude all of the gain.