NOTE 2 - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (continued)
In the six-month period ended June 30, 2021 we recognized $4,537,000, or 71%, in revenue from deferred revenue outstanding as of December 31, 2020.
In the three months ended June 30, 2021, two customers (including affiliates of such customers) accounted for 20% and 10%, respectively, of our total revenue. In the six months ended June 30, 2021, three customers (including affiliates of such customers) accounted for 20%, 10%, and 10%, respectively, of our total revenue. In the three and six months ended June 30, 2020, one customer accounted for 16%, and 17%, respectively, of our total revenue.
Three customers represented 19%, 14% and 11%, respectively, of total accounts receivable as of June 30, 2021. Three customers with long standing relationships with the Company represented 25%, 13% and 13%, respectively, of total accounts receivable as of December 31, 2020.
Deferred Costs (Contract acquisition costs)
We capitalize initial and renewal sales commissions in the period in which the commission is earned, which generally occurs when a customer contract is obtained, and amortize deferred commission costs on a straight-line basis over the expected period of benefit, which we have deemed to be the contract term, except when the commission payment is expected to provide economic benefit for a period longer than the contract term, such as for new customer or incremental sales where renewals are expected, and renewal commissions are not commensurate with initial commissions. As a practical expedient, we expense sales commissions as incurred when the amortization period of related deferred commission costs would have been one year or less.
The table below summarizes the deferred commission costs as of June 30, 2021 and December 31, 2020:
| | | | | | |
| | June 30, | | December 31, |
(in thousands) | | 2021 | | 2020 |
Deferred costs - current | | $ | 142 | | $ | 152 |
Deferred costs - noncurrent | | | 66 | | | 77 |
Total deferred costs | | $ | 208 | | $ | 229 |
Amortization expense associated with sales commissions was included in selling and marketing expenses on the statements of operations and totaled $52,000 and $99,000 for the three- and six-month periods ended June 30, 2021, respectively, and $55,000 and $111,000 for the three- and six-month periods ended June 30, 2020, respectively. There were 0 impairment losses for these capitalized costs for the three and six months ended June 30, 2021 and 2020.
Stock-Based Compensation
The Company periodically issues options, warrants, restricted stock units (“RSUs”), and shares of its common stock as compensation for services received from its employees, directors, and consultants. The fair value of the award is measured on the grant date. The fair value amount is then recognized as expense over the requisite vesting period during which services are required to be provided in exchange for the award. Stock-based compensation expense is recorded by the Company in the same expense classifications in the statements of operations, as if such amounts were paid in cash.