18. Contract assets, trade and other receivables

Current assets	2022 £000	2021 £000
Amounts due from construction contract customers (note 17):
Trade receivables and other	27,004	35,885
Contract assets	74,898	16,288
Total	101,902	52,173
Other receivables	6,062	6,212
Prepayments and accrued income	7,580	7,331
Amounts due from JVs and associates	2,315	2,131
	117,859	67,847

Non-current assets	2022 £000	2021 £000
Contract assets, trade and other receivables	4,881	4,368
	4,881	4,368

Contract assets of £74,898,000 (2021: £16,288,000) mainly reflect the Group's right to consideration for work completed but not billed at the year end on construction contracts. The increase in the year mainly reflects the impact of steel and other input price rises, together with higher steel purchases to meet production requirements in 2023.

The average credit period taken on revenue, calculated on a count-back basis to make appropriate allowance for monthly revenue phasing, is 69 days (2021: 31 days). No interest is charged on receivables.

The directors consider that the carrying amount of trade and other receivables approximates to their fair value.

Before accepting any new customer, the Group uses an external credit rating agency to assess the potential customer's credit quality and defines credit limits by customer. It is Group policy that adequate credit insurance is taken out on all customers to manage the exposure that may arise as the contractual work proceeds. The Group's executive risk committee reviews situations where adequate credit insurance on the Group's customers cannot be purchased in the present economic climate as required. The Group has rigorous procedures in place for monitoring and obtaining settlement of retentions in a prompt manner. Overdue retentions at 26 March 2022 were £nil (2021: £nil).