IRS on like-kind exchange

Taken from IRS website, I remember two requirements, buying and selling have to be done within a limited time frame, say one year (not sure), you have to spend more on buying than selling. For instance, if you sell 10 houses for $1million, you need to buy a new one, or ones for at least $1million to get tax free (or deferred).   Like-Kind Exchanges - Real Estate Tax Tips

Generally, if you exchange business or investment property solely for business or investment property of a like-kind, no gain or loss is recognized under Internal Revenue Code Section 1031. If, as part of the exchange, you also receive other (not like-kind) property or money, gain is recognized to the extent of the other property and money received, but a loss is not recognized. Section 1031 does not apply to exchanges of inventory, stocks, bonds, notes, other securities or evidence of indebtedness, or certain other assets. Like-Kind Property Properties are of like-kind, if they are of the same nature or character, even if they differ in grade or quality. Personal properties of a like class are like-kind properties. However, livestock of different sexes are not like-kind properties. Also, personal property used predominantly in the United States and personal property used predominantly outside the United States are not like-kind properties. Real properties generally are of like-kind, regardless of whether the properties are improved or unimproved. However, real property in the United States and real property outside the United States are not like-kind properties.