Table:
|  | As of January 1,2018 | As of December 31,2018 | As of December 31,2019 |
| --- | --- | --- | --- |
|  | NT$(In Thousands) | NT$(In Thousands) | NT$(In Thousands) |
| Sales of goods and services | $3,951,414 | $932,371 | $1,470,195 |
| Current | $3,951,414 | $932,371 | $988,115 |
| Noncurrent | — | — | 482,080 |
| Total | $3,951,414 | $932,371 | $1,470,195 |
Paragraphs:
The movement of contract liabilities is mainly caused by the timing difference of the satisfaction of a performance of obligation and the consideration received from customers.
The Company recognized NT$3,815 million and NT$616 million, respectively, in revenues from the contract liabilities balance at the beginning of the period as performance obligations were satisfied for the years ended December 31, 2018 and 2019.
Question:
What causes the  movement of contract liabilities?
Answer: mainly caused by the timing difference of the satisfaction of a performance of obligation and the consideration received from customers.