What "tax-free" actually means on a return
Deferred, sheltered, and never-taxed are three different things.
Real estate marketing uses "tax-free" for three mechanisms that behave nothing alike. Learn the difference at Year 2, because every strategy decision after this depends on which one is actually in play.
Sheltered
Depreciation offsets rental income on paper while the property appreciates in fact. The income was real; the tax bill is smaller. But depreciation is a loan from your future self — it reduces your basis, and the IRS collects it back as recapture when you sell. Unless you never sell (see below).
Deferred
A 1031 exchange rolls a gain into the next property untaxed. The tax is not gone; it is riding along in your reduced basis, waiting for a sale that triggers it.
Never-taxed
The step-up in basis at transfer erases the deferred gain entirely. This is the only genuinely tax-free mechanism of the three — and it only pays off if you held the chain long enough to reach it.
The whole twenty-year architecture of this site is these three words in order: shelter while you hold, defer when you trade, step up when you transfer.