If you frequently transfer money out of savings, or cover checking overdrafts with a linked savings account, you’ve likely discovered there’s a limit to how often you can do this in a month. Exceed six withdrawals per statement cycle and your bank will warn you at best, or close your account at worst.

But before unloading your anger at your bank, or moving your savings to a seemingly friendlier institution, know that banks have no say in this. The mandate comes down from the Federal Reserve in a rule called Regulation D.

The six-withdrawal limit applies to all liquid savings instruments, so that includes savings and money market accounts. It also applies equally to banks and credit unions. And while the Fed doesn’t dictate fees, most institutions will ding you with a charge – often $10 – to teach you that your savings account can’t be used like a checking account.

If you’re a first-time offender, you may escape with a warning, or may be able to score a one-time courtesy waiver. But even if you pay the fee, repeatedly exceeding the limit will eventually lead the bank to close your account, as they simply can’t abide by their own Fed requirements if you keep breaking the rules.

Fortunately, only withdrawals authorized online, by phone, via bill payment or as auto-transfers count toward the six. So if you’ve hit your monthly limit but still need to take out funds, you can avoid the penalty by withdrawing at a branch or ATM, or by requesting a mailed check.

With an understanding of the rule, and the ability at many institutions to see how many withdrawals remain for the month, most consumers can plan accordingly to use their account as the Fed requires, and avoid their savings being diminished by fees.