Hi imran,
WIP accounts are usually used to "store" all costs and revenues in balance sheet accounts until the costs and revenues are realized. Here is a simplified example:
As the project goes along, all costs for horus, expenses and items are "stored" in WIP accounts in the company's balance sheet. If you sent a customer an invoice, no revenue is generated. Rather than that, a posting on a WIP account (PRO-WIP-INV-ONACC in my example) occurs to ensure that all transactions do not generate a profit / loss.
The profit/loss generation occurs with the estimate process. That is, when running the project estimate, the WIP cost postings are reversed and the costs are recognized in a company's P&L Statement. At the same time revenues are recongnized. The Revenue recognition occurs through a WIP-Salesvalue account that is reversed once the project is eliminated.
Please have a look at the sample transactions illustrated above. Hope they will clarify the use of ledger accounts in Fixed Price Project with POC.
All the best,
Ludwig