The responsible party or the responsible party’s guarantor is liable to a claimant for interest on the amount paid in satisfaction of a claim under this Act for the period described in subsection (b). The responsible party shall establish a procedure for the payment or settlement of claims for interim, short-term damages. Payment or settlement of a claim for interim, short-term damages representing less than the full amount of damages to which the claimant ultimately may be entitled shall not preclude recovery by the claimant for damages not reflected in the paid or settled partial claim.
If the guarantor offers to the claimant an amount equal to or greater than that finally paid in satisfaction of the claim, the period described in paragraph (1) does not include the period beginning on the date the offer is made and ending on the date the offer is accepted. If the offer is made within 60 days after the date on which the claim is presented under section 2713(a) of this title, the period described in paragraph (1) does not include any period before the offer is accepted.
The interest paid for claims, other than Federal Government cost recovery claims, under this section shall be calculated at the average of the highest rate for commercial and finance company paper of maturities of 180 days or less obtaining on each of the days included within the period for which interest must be paid to the claimant, as published in the Federal Reserve Bulletin.