Here's why Apple just raised $6.5 billion in debt - even though it's sitting on $178 billion in cash

Apple sold $6.5 billion in bonds on Monday, according to Bloomberg.

That's the same Apple that last week announced an record-breaking $18 billion profit over the holiday quarter.

It's reasonable to ask: why would Apple - a company with $178 billion in cash - need a loan?

In short: taxes.

The vast majority of Apple's cash hoard is held offshore.

Apple can defer taxes on that cash until it decides to bring it back to the U.S.

Apple doesn't want to bring the money home, though. It could pay up to 35% of whatever it brings back to Uncle Sam, which could easily be a multi-billion dollar tax bill.

Apple wants a tax repatriation holiday, like the one recently proposed by Senators Barbara Boxer and Rand Paul.

The Boxer-Paul would tax cash Apple brought home at 6.5%, much lower than the rate it would otherwise pay.

But the prospects for the Boxer-Paul plan aren't looking good. Senator Orrin Hatch, Chair of the Senate Finance Committee, has already expressed skepticism about it. And this bill hasn't even been introduced yet.

Meanwhile, Apple still needs cash in the US. The $6.5 billion it raised will go towards stock repurchases, dividend payments, and debt repayments, according to Bloomberg.

With corporate taxes so high, and interest rates so low, it's much cheaper for Apple to raise debt and pay it back with interest than to repatriate cash.

Unless we see corporate tax reform, Apple will probably keep raising money this way for the foreseeable future.