Howard told Digital Spy at the Warner Music Brit Awards after-show boat party that the group were supported by a grant from The Prince's Trust when they first formed in 1994.
"We bought our first PA system with [the money] and still have it now, it comes out for family weddings," Howard revealed.
"I guess you could say we owe Prince Charles £250."
Muse opened this year's Brit Awards broadcast on ITV, with rumours that they had spent a six-figure sum on a 300-piece orchestra, choir, lasers and pyrotechnics for their performance.
Kate Hudson, Nick Grimshaw and Holly Willoughby were among the celebrities in attendance at the Warners boat party, along with double Brits winner Emeli Sandé, who closed the main ceremony at the O2 Arena.
Brit Awards 2013 - photo gallery: