1031 exchange

IRS §1031 — defer capital gains tax by exchanging one investment property for another like-kind property.

Sell investment property A, identify replacement property B within 45 days, close on B within 180 days, and use a qualified intermediary to hold the cash in between. Defer all gain if the replacement is bigger (price + debt) than the relinquished; partial defer otherwise. Personal residences don't qualify.