21. Trade accounts receivable
| In CHF'000 | 31.12.2009 | 31.12.2008 |
| Trade accounts receivable | 302 361 | 355 978 |
| Less: provision for impairment | -26 754 | -21 839 |
| Trade accounts receivable related parties | 6 286 | 11 705 |
| Trade receivables – net | 281 893 | 345 844 |
| Amounts due from customers for contract work, of which kCHF -1'860 provision (2008: kCHF -1'252) | 10 126 | 8 088 |
| Total | 292 019 | 353 932 |
Before accepting new customers, the Group performs a credit scoring to assess the potential customer's credit quality and defines credit limits by customer. Limits and scoring attributed are regularly reviewed. Furthermore, for low value added business deliveries, the Group usually works on a back to back basis.
The following table summarizes the movement in the provision for impairment:
| In CHF'000 | 2009 | 2008 |
| January 1 | -21 839 | -7 851 |
| Change in scope | – | -60 |
| Provision for impairment charged to income statement | -13 084 | -16 743 |
| Utilization | 1 883 | 762 |
| Reversal | 6 217 | 1 720 |
| Translation effects | 69 | 333 |
| December 31 | -26 754 | -21 839 |
The creation and release of provision for impairment are included in other operating expenses (sales expenses) in the income statement. Provisions recognized for the impairment of trade receivables amount to kCHF -13 084 (2008: kCHF -16 743). Amounts charged to the provision for impairment account are written-off when there is no expectation to recover additional cash.
The following table contains details of the trade accounts receivables ageing that are not overdue under the contractual payment terms and an analysis of overdue amounts that are not impaired:
| In CHF'000 | 31.12.2009 | 31.12.2008 |
| Not overdue | 168 605 | 133 958 |
| Past due and not impaired: | ||
| – not more than one month | 55 410 | 75 655 |
| – more than one month and not more than three months | 34 050 | 79 931 |
| – more than three months and not more than six months | 12 212 | 44 814 |
| – more than six months and not more than one year | 6 451 | 7 971 |
| – more than one year | 5 165 | 3 515 |
| Total trade accounts receivable, net | 281 893 | 345 844 |