Harmonix founders Alex Rigopulos and Eran Egozny are leading a lawsuit from a number of the developer's former shareholders against current owners Viacom.
It is alleged the MTV-owning company, which put Harmonix up for sale last month, is "manipulating costs" in an attempt to try and avoid bonus payments.
Gamasutra reports that the dispute concerns the initial deal penned between the pair when Harmonix was initially acquired in 2006. The studio believes bonuses of 3.5 times any gross profit made beyond $32m throughout 2007.
The same conditions apply for 2008, though only to profit over $45m.
Now the aggrieved group wants to "recover damages arising from Viacom's manipulation of these earn-out payments by diverting opportunities from Harmonix for its own benefit in breach of the implied covenant of good faith and fair dealing that inheres in Viacom's contract with Harmonix."
It is alleged that some of the 2007 money remains unpaid, and nothing relating to 2008 has been received. The site speculates that the disagreement is one of the key reasons behind Viacom's decision to sell off the studio.
The suit also alleges that Viacom "decided to forego the opportunity to reduce EA's distribution fees during 2008 (or in any other way enhance Harmonix's net income or Gross Profit for 2008), and instead demanded benefits for itself (rather than Harmonix) in exchange for allowing EA to continue distributing Rock Band."