The law states that basis is reduced by depreciation allowed or allowable. If you don't take depreciation, the IRS will reduce your basis when sold anyway as if you had taken depreciation. So even if you don't take depreciation the IRS treats it as if you did.the IRS will recapture depreciated allowed are allowable at a rate of 25%.
When reporting the sale of the rental property you are required to reduce the basis of the property for allowable depreciation regardless of whether the depreciation deduction was taken or not. For more information, refer to Publication 544, Sales or Other Dispositions of Assets, the Instructions 4797, Sale of Business Property, and Publication 527, Residential Rental Property (including vacation homes).