Table:
|  | Year Ended December 31, |  |
| --- | --- | --- |
|  | 2019 | 2018 |
| Beginning of period balance | $2,881 | $— |
| Commission costs and upfront payments to a customer capitalized in period | 4,141 | 4,864 |
| Amortization of contract assets | (2,444) | (1,983) |
| End of period balance | $4,578 | $2,881 |
Paragraphs:
Note 3. Revenue from Contracts with Customers
Contract Assets
Our contract assets consist of capitalized commission costs and upfront payments made to customers. The current portion of capitalized commission costs and upfront payments made to customers are included in other current assets within our consolidated balance sheets. The non-current portion of capitalized commission costs and upfront payments made to customers are reflected in other assets within our consolidated balance sheets. Our amortization of contract assets during the years ended December 31, 2019 and 2018 were $2.4 million and $2.0 million, respectively. There were no amortized commission costs during the year ended December 31, 2017.
We review the capitalized costs for impairment at least annually. Impairment exists if the carrying amount of the asset recognized from contract costs exceeds the remaining amount of consideration we expect to receive in exchange for providing the goods and services to which such asset relates, less the costs that relate directly to providing those good and services and that have not been recognized as an expense. We did not record an impairment loss on our contract assets during the years ended December 31, 2019, 2018 and 2017.
The changes in our contract assets are as follows (in thousands):
Question:
What does the company's contract assets consist of?
Answer: capitalized commission costs and upfront payments made to customers.