The central defender, who earns £70,000-a-week at Arsenal, will increase his salary to £100,000 if United and Arsenal agree a transfer fee, the Telegraph report.
Belgium international Vermaelen, 28, joined Arsenal from Ajax for £10 million in 2009 and enjoyed a stellar first season, however he lost his place in the side last year after Per Mertesacker and Laurent Koscielny formed a successful partnership.
As well as his age and squad role status, Vermaelen only has a year remaining on his contract, meaning Arsenal will not make a profit from any transfer fee.
Incoming United coach Louis van Gaal remains keen to sign Borussia Dortmund defender Mats Hummels, however Vermaelen is a cheaper - and arguably inferior - alternative.
United supporters are likely to be underwhelmed by Vermaelen's supposed arrival, whilst Arsenal supporters will be left enraged days after Manchester City confirmed the signing of Bacary Sagna.
Arsène Wenger had originally targeted a goalkeeper and right-back, yet should Vermaelen join United then he will require more defensive cover.
Arsenal have been forced to sell a number of players with a year remaining on their contracts, and although Vermaelen is not as pivotal as Samir Nasri or Robin van Persie were when they left, the manner of his departure will leave Gooners with a familiar feeling of disappointment.