It was a terrible idea back in 2004. It is still a terrible idea—and two very different analyses help explain why.

The first, by the congressional Joint Committee on Taxation, estimates that while cutting taxes for one year on repatriated earnings briefly generates new revenue, it significantly increases the deficit even within Congress’ usual 10-year budget window.

According to a new JCT estimate, such a holiday would boost federal revenues by about $19 billion over the first two years as firms pay some tax on funds they would otherwise have kept overseas tax-free. But since multinationals are getting a tax break for bringing money back they would eventually have returned anyway (at higher rates), JCT figures the tax holiday would add almost $96 billion to the deficit over a decade. So much for free money.

The second study, by financial accounting experts Michaele Morrow of Northeastern University and Robert C. Ricketts of Texas Tech, looks closely at how firms responded to the 2004 tax break. Their fascinating conclusion: For many multinationals, the benefit of the holiday was not primarily tax savings at all. Rather, it provided an easy way to manage the earnings they report to shareholders by manipulating their financial statements.