Since 2014, European regulators have been investigating Apple (AAPL) along with a number of other American companies they believe could be exploiting tax laws in Ireland and other countries, sheltering profits there in order to reduce how much they owe the IRS in the U.S.

The European Commission is weighing whether to levy a higher tax rate on Apple, which could allow it to collect more than $8 billion in back taxes, according to Bloomberg Intelligence‘s calculation. Such a decision, which the report said could happen in March, would mean that Apple’s tax bill would be as much as homebuilder D.R. Horton (No. 354 on the Fortune 500) makes in revenue per year.

The majority of Apple’s revenue, which was $182.8 billion last year, comes from abroad with a foreign tax rate of around 1.8%, Bloomberg said. The ruling could raise that rate to 12.5%.

The company has $205.7 billion in cash on hand, so $8 billion would represent a hit of less than 4%.

In December, Apple CEO Tim Cook told 60 Minutes that allegations that Apple is using foreign tax shelters to dodge paying Uncle Sam were “total political crap,” and that, “Apple pays every tax dollar we owe.” But at the end of 2015, Apple agreed to pay Italy’s tax authorities the equivalent of $348 million to settle a similar probe.

Amazon (AMZN), Starbucks (SBUX), and McDonald’s (MCD) are also under investigation in Europe for their tax structures there.