The movements in the allowance for doubtful debts during the year are as follows:
| 2017 | 2016 | |||||||
| RMB million | RMB million | |||||||
|
At January 1 |
37 | 33 | ||||||
|
Impairment loss recognized |
8 | 14 | ||||||
|
Impairment loss written back |
— | (1 | ) | |||||
|
Uncollectible amounts written off |
(8 | ) | (9 | ) | ||||
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At December 31 |
37 | 37 | ||||||
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