My answer to What legal options I have as an IT contractor, if the client doesn't pay me money ?
Answer by Ken Larson:
Many federal contracts are funded incrementally, usually based on the government fiscal year that runs from 1 October to 30 September. Although the government may negotiate dollar price ceilings for cost plus and time and materials contracts or firm, fixed total price arrangements, the contracts themselves may be incrementally funded, particularly if they extend over two government fiscal years. A contract may contain negotiated prices or a cost ceiling but also specify an incremental funding value.
The contractor is required to inform the government when actual costs incurred plus obligations to suppliers or payroll on a specific contract reach certain thresholds of the current incremental funding specified in the contract (usually 80%). The government is then obligated to further fund the contract.
In the event the contract is not funded further, the contractor has the right to stop work before he exceeds the incremental funding. Some contractors choose to operate on "risk," continuing to perform on a contract while exceeding the incremental funding in booked cost and obligations.
The government is under no obligation to reimburse the contractor for invoiced amounts exceeding incremental funding. Nearing the end of a government fiscal year, a contractor may find delays in funding reaching all the way to congress. This situation must be managed with the government contracting officer.