Embodiments of the invention provide systems and methods for fair share allocation of inventory levels throughout a supply chain. According to one embodiment, a first round main Linear Programming (LP) solve can generate an initial solution. Post-processing heuristics for fair sharing can be applied to the first round solve of the main LP. Circular sourcing heuristics can be applied to the first round solve when adjusting for fair sharing allocation requirements. For example, applying the circular sourcing heuristics to the first round solve of the main LP can comprise determining a firmed supply surplus and shortage based on a demand picture from the first round solve of the main LP adjusted for fair sharing. A second round main LP solve can be executed using the fixed inter-organizational transfer variables and fixed supply towards independent demand variables from the post-processing heuristics.