Contractors may only use an offset if what two conditions are met?

The contractor certifies to the contracting officer that, to the best of the contractor's knowledge and belief, the contractor is entitled to the offset in the amount requested.

The contractor proves that the certified cost or pricing data were available before the "as of" date specified on the Certificate of Current Cost or Pricing Data but were not submitted.

Fewer than one-third of defective pricing cases require the Government to collect interest on overpayment.

The understated data were known by the contractor to be understated before the "as of" date specified on the Certificate of Current Cost or Pricing Data.