Since unveiling its first Surface in mid-2012, Microsoft Corporation (NASDAQ:MSFT) has lost at least $1.2 billion trying to help the struggling tablet lineup succeed. To be fair, much of that amount stems from a $900 million writedown Microsoft took for "inventory adjustments" around this time last summer. But Microsoft's total cost of Surface revenue has already exceeded sales by at least the remaining $300 million, including a $45 million loss during its most recent quarter alone.

But according to the Fool's Steve Symington in the following video, those losses might be about to increase even more thanks to a new Surface incentive program aimed at winning over current Apple (NASDAQ:AAPL) loyalists. Specifically, through the end of July, Microsoft is offering up to $650 in store credit to MacBook Air owners willing to "trade up" to a Surface Pro 3 -- a hefty sum considering Microsoft's entry-level Surface Pro 3 starts at just $799.

More likely, Steve says, is that Microsoft is using the incentive to steer Apple's MacBook Air users toward the premium, higher-margin Surface Pro 3 models. But even then, Microsoft could have its work cut out for it persuading a large enough number of Apple loyalists to jump ship. To hear Steve's full take on what this means for both Apple and Microsoft, please watch the following video.

Steve Symington owns shares of Apple. The Motley Fool recommends Apple and owns shares of Apple and Microsoft. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.