The $25,000 penalty
It is assessed per form, per year, and it does not scale with the size of your business. A dormant LLC with no revenue faces the same number as an operating one.
How it accumulates
The instructions are direct: “A penalty of $25,000 will be assessed on any reporting corporation that fails to file Form 5472 when due.” If the failure continues more than 90 days after the IRS notifies you, “an additional penalty of $25,000 will apply … for each 30-day period (or part of a 30-day period) during which the failure continues.”
Two things follow. Missing several years means several penalties, not one. And once a notice arrives, the clock is measured in months, so the cost of doing nothing climbs fast.
If you have never filed
Filing late beats not filing, and filing before the IRS contacts you is materially better than after: the 90-day clock that multiplies the penalty only starts with their notice.
Late filings are normally submitted for each missed year with a reasonable cause statementexplaining why. Reasonable cause is a real relief route rather than a formality: it turns on your specific facts, and “I did not know it existed” is weaker on its own than a documented account of what happened.
If you are several years behind, this is the point to talk to someone who handles these professionally. A page on the internet, this one included, is not the right instrument for a multi-year catch-up.
What the penalty is not
It is not a tax. Form 5472 reports information, not income, and filing it does not create a US tax liability by itself. People sometimes delay expecting a bill on the other side. There is none, which is what makes the $25,000 so avoidable.