[34] Contract balances

Contract assets stood at €403.3 million (December 31, 2022: €528.8 million); most of this amount, €390.6 million (December 31, 2022: €508.0 million), was attributable to goods and services provided in the project business that have not yet been billed.

Of the contract liabilities, €582.7 million was attributable to project business contracts with a net debit balance due to customers (December 31, 2022: €640.3 million) and €190.6 million to prepayments received from customers (December 31, 2022: €185.8 million). The revenue recognized in the reporting period that was included in the contract liability balance at the beginning of the period amounted to €721.1 million (2022: €814.7 million).