Plan Accounting Treatment of Withdrawal Liability Receivable

[Mengistu]

When Withdrawal Liability Receivable is due and should be recognized/recorded in accounting?  There are some cases that employers are reluctant to start paying their withdrawal liabilities when assessment has been completed and they are notified with a payment plan schedule. Should it be recorded as Receivable in anyway or should it be waited until the employer accept it and start payments?

Thank you.