Federal contractors are required to submit Incurred Cost Submissions (ICS) to reconcile their actual indirect expenses for a fiscal year with the provisional indirect costs billed under cost-type and time and materials contracts. ICS must be submitted six months after the end of the fiscal year and cover every business unit holding applicable contracts. ICS functions similarly to personal income tax returns, where government contractors reconcile their actual costs incurred with provisional estimates used for billing, ensuring costs are allowable.