Yes, you do need to report the gain and you do need to determine the amount of depreciation you should have taken for the period that it was a rental.
Although the period of time that you owned the home and used it as your primary home does qualify for the exclusion, the period of time you were not living in the home does not qualify. Since you rented it for approximately 3 out of the 8 years that you owned it, approximately 37.5% of the gain will be capital gains. Of that, any depreciation that you were required to take during the years you rented it would be potentially taxed at a higher rate.
If you do not know how much depreciation you took during those years, you will have to refer to your tax returns for the years that you used it as a rental. If you have an asset worksheet from the last year you rented it, that should have the prior depreciation you could have taken and the depreciation you took that year. The sum would be the total depreciation. If you do not have that, your Schedule E for each year will have the depreciation you took. You would add those together for the total depreciation.
Allowable depreciation must be reported whether or not you took advantage of the deduction in the years that you rented the property.
