23 Receivables
| 2008 $000  | 
            2007 $000  | 
        |
|---|---|---|
            Current | 
            ||
| Receivables | 5,979 | 4,238 | 
| Allowance for impairment of receivables | (14) | (47) | 
| Accrued revenue | 3,558 | 2,341 | 
| GST receivable | 9,180 | 6,819 | 
| Other receivables – external works | 1,256 | 323 | 
| 19,959 | 13,674 | |
| Prepayments | 2,127 | 596 | 
| 22,086 | 14,270 | |
            Reconciliation of changes in the allowance for impairment of receivables: | 
            ||
| Balance at start of year | 47 | 104 | 
| Doubtful debts expense recognised in the income statement | 0 | 6 | 
| Amounts written off during the year | (33) | (63) | 
| Balance at end of year | 14 | 47 | 
            Ageing of receivables past due but not impaired based on the information provided to senior management, at balance sheet date: | 
            ||
| Not more than 3 months | 1,850 | 49 | 
| More than 3 months but less than 6 months | 85 | 43 | 
| More than 6 months but less than 1 year | 1 | 2 | 
| More than 1 year | 2 | 49 | 
| 1,938 | 143 | |
            Receivables individually determined as impaired at the balance sheet date: | 
            ||
| Carrying amount, before deducting any impairment loss | 14 | 47 | 
| Impairment loss | 0 | (47) | 
| 14 | 0 | 
The PTA does not hold any collateral as security or other credit enhancements relating to receivables.
