Lending your bank account can cost you a tax-fraud accusation — you, not whoever uses it

It is one of the most normalized favors there is: "deposit it into my account and I'll pass it to you," the aunt who collects the nephew's rent, the "account-less" brother who gets his paycheck deposited into yours. What happens if you lend your bank account? Popular logic assumes that, since the money isn't yours, neither is the problem. The law assumes exactly the opposite: before the SAT, the movements in your account are yours until you prove — with evidence, not your word — otherwise. And the one who carries the burden of proof is you, not the real owner of the money.

The SAT sees your accounts. All of them, and without asking your permission

Financial institutions are required to hand over to the tax authority the information on their clients' accounts, deposits, services and trusts (art. 32-B CFF); the request travels through the CNBV and bank secrecy does not operate against the SAT's audit powers. On top of that, cash deposits exceeding MXN $15,000 a month are reported automatically (art. 55-IV LISR). We trace the full map of who sees what — SAT, UIF and the Prosecutor's Office — in the triangle that sees your money; the executive summary: the idea of the "non-tax account" is a dinner-table myth, as we explain in every account is a tax account.

The exact mechanics by which they tax you on what wasn't yours

For someone with business activity and accounting, unrecorded deposits are presumed taxed income (art. 59, section III CFF). For an employee or a person with no registered activity, the tax discrepancy of art. 91 LISR applies: when your outlays — expenses, acquisitions, deposits in your accounts — exceed your declared income, the SAT notifies you of the difference and you have 20 days to prove the source. Whatever you can't explain becomes omitted income with inflation adjustment, late-payment surcharges and a fine. The larger outcome is codified: tax fraud and its equivalent (arts. 108 and 109 CFF) carry prison — and they are crimes of the account holder, because it was in the holder's sphere that the income was "omitted." One floor below waits the scenario nobody contemplates when doing the favor: if the money that passed through your account has an illicit origin, your account was the vehicle — and that conversation is no longer with the SAT (art. 400 Bis of the Federal Criminal Code). You need not have earned a single peso: the risk belongs to the name on the account contract.

How family money moves the right way (and how to defend yourself if you already lent your account)

The legitimate movement of family money has its channels, all documentable: gifts between spouses, ascendants and descendants are exempt from ISR with no limit (art. 93-XXIII LISR) — but if your loans, gifts and prizes for the year together exceed MXN $600,000, they are reported in your annual return, and omitting that line turns exempt income into taxed income through one careless click; family loans go with a contract bearing fecha cierta (a legally certain date) and a bank trail. The fine print is in loans and gifts between family members. For whoever has already lent the account: the defensive file is built today, not when the letter arrives — full traceability of each deposit and its mirror outflow, documentation of the real ownership of the money, and voluntary correction where there is any to be made, which is still the cheapest word in tax law. Labels: moving family money documented through the right channels — safe; having received deposits from third parties with perfect traceability in and out — defensible, but uphill and with the burden of proof on you; lending your account recurrently for someone else's operation — red zone, tax and potentially criminal.