The AI bill came due — and your tax bill works the same way.

Three of the largest AI spenders reported earnings this week. One made money. Two spent more than they brought in — and the market noticed immediately. The same math runs on an unpaid tax balance, except the IRS never waits for an earnings call.

This week three of the largest AI spenders all reported results — and the scoreboard split cleanly. Microsoft’s cloud business kept growing (Azure revenue up 48%) and its free cash flow stayed positive at about $18.6 billion. Alphabet and Amazon went the other way: Alphabet spent $51.4 billion on capital projects in the quarter and its free cash flow went negative, about minus $9.1 billion, and its shares fell roughly 9%. Amazon spent $77.3 billion in a single quarter, reported earnings of $1.89 a share against about $1.96 expected, and its trailing twelve-month free cash flow swung to minus $42.4 billion — from plus $14.8 billion a year ago. Its shares fell about 7% after hours.

The backdrop isn’t a weak economy. The Bureau of Economic Analysis reported Thursday that the U.S. economy grew at a 3.4% annual rate in the third quarter (its advance estimate, up from 2.2% in the second quarter), while September prices were still hot: the PCE price index rose 3.6% from a year earlier, and core PCE — excluding food and energy — rose 3.1%. The Federal Reserve held its benchmark rate at 3.75% to 4.00% the day before.

Free cash flow is the number that matters

Revenue is the press release. Free cash flow is the cash box: the cash a business brings in, minus what it spends on things that last for years — chips, buildings, power. Amazon grew sales 12% — and still spent more than it brought in: sales rose to $201.9 billion, operating income jumped 61%, and the cash still went out faster than it came in, because the AI buildout cost $77.3 billion in three months.

None of this is investment advice, and none of it is a prediction about any company’s stock. The point is the logic — because the same logic runs on a tax balance.

The same math, on your tax balance

An unpaid tax balance works like a company that keeps spending more than it brings in. The IRS charges interest on underpayments at 7% a year, compounded daily, for the fourth quarter of 2026 — and that rate is set by the IRS’s own quarterly formula, not by the Federal Reserve, so the Fed holding rates this week changes nothing about it. On a $10,000 balance, that is roughly $178 of interest over the 92 days of the quarter, before any penalties. The balance does not shrink on its own, and it does not wait for a better quarter.

The difference is that a company of Amazon’s size can raise $48 billion of debt in a quarter — Amazon did exactly that — and keep building. A taxpayer with an unpaid balance has fewer levers, but they exist: an installment agreement can potentially spread what you owe into monthly payments, penalty abatement can potentially reduce the penalties, and an Offer in Compromise can potentially settle for less than the full amount, if the taxpayer qualifies. None of those are guaranteed, and none of them start by themselves.

Alex Volkov, CPA is a New York-licensed CPA with over two decades in accounting, focused on resolving IRS tax problems — back taxes, liens, levies, garnishments, and audits — for individuals and businesses nationwide.