49 CFR §1018.52

1. (a)The Board may not accept a percentage of a debtor's profits or stock in a debtor's corporation in compromise of a claim. In negotiating a compromise with a business concern, consideration is given to requiring a waiver of the tax-loss-carry-forward and tax-loss-carry-back rights of the debtor.
2. (b)If two or more debtors are jointly or severally liable, collection action is not withheld against one debtor until the other or others pay their share. The amount of a compromise with one debtor is not considered a precedent or binding in determining the amount which will be required from other debtors jointly and severally liable on the claim.