Section 4.704 - Calculation of retention periods(a) The retention periods in 4.705 are calculated from the end of the contractor's fiscal year in which an entry is made charging or allocating a cost to a Government contract or subcontract. If a specific record contains a series of entries, the retention period is calculated from the end of the contractor's fiscal year in which the final entry is made. The contractor should cut off the records in annual blocks and retain them for block disposal under the prescribed retention periods.(b) When records generated during a prior contract are relied upon by a contractor for certified cost or pricing data in negotiating a succeeding contract, the prescribed periods shall run from the date of the succeeding contract.(c) If two or more of the record categories described in 4.705 are interfiled and screening for disposal is not practical, the contractor shall retain the entire record series for the longest period prescribed for any category of records.48 FR 42113, Sept. 19, 1983, as amended at 75 FR 53142 , Aug. 30, 2010