26. Current/Non-current contract assets/(liabilities)

Millions of euro Non-current Current
  at Dec. 31, 2020 at Dec. 31, 2019 at Dec. 31, 2020 at Dec. 31, 2019
Contract assets 304 487 176 166
Contract liabilities 6,191 6,301 1,275 1,328

Non-current assets deriving from contracts with customers (contract assets) refer mainly to assets under development resulting from public-to-private service concession arrangements recognized in accordance with IFRIC 12 and which have an expiration of beyond 12 months (€297 million). These cases arise when the concession holder has not yet obtained full right to recognize the asset from the grantor at the hypothetical conclusion of the concession arrangement in that there remains a contractual obligation to ensure that the asset becomes operational. At December 31, 2020, the figure includes investments for the year in the amount of €649 million.

Current contract assets mainly concern construction contracts in progress (€154 million) to be invoiced, payments on which are subject to the fulfillment of a performance obligation.
The figure at December 31, 2020 for non-current contract liabilities is mainly attributable to distribution in Italy (€3,359 million), Spain (€2,400 million) and Romania (€425 million) as a result of the accounting treatment of revenue from connections of new customers with invoicing in advance of the completion of the performance obligation.

Current contract liabilities include the contractual liabilities related to revenue from connections to the electricity grid expiring within 12 months in the amount of €859 million, mainly recognized in Italy and Spain, as well as liabilities for construction contracts in progress (€387 million).