Annual report pursuant to Section 13 and 15(d)

Receivables and Unbilled Receivables

Receivables and Unbilled Receivables
12 Months Ended
Dec. 31, 2020
Receivables [Abstract]  
Receivables and Unbilled Receivables Receivables and Unbilled Receivables
Receivables, net and unbilled receivables, net as of December 31, 2020 and 2019, respectively, were as follows (in thousands):
  2020 2019
Receivables, net $ 55,471  $ 70,630 
Unbilled receivables, net 22,358  46,279 
Total $ 77,829  $ 116,909 

Receivables, net are recorded at face value less an allowance for credit losses of approximately $1.5 million and $396 thousand as of December 31, 2020 and 2019, respectively.

The allowance for credit loss is determined using a combination of specific reserves for accounts that are deemed to exhibit credit loss indicators and general reserves that are judgmental determined using loss rates based on historical write-offs and consideration of recent forecasted information, including underlying economic expectations. The credit loss reserves are updated quarterly for most recent write-offs and collections information and underlying expectations, which for the year ended December 31, 2020 included consideration of the current and expected future economic and market conditions surrounding the COVID-19 pandemic.

A summary of activity in our allowance for credit losses for the year ended December 31, 2020 is as follows (in thousands):

Balance as of December 31, 2019 $ 396 
Change in estimates 1,767 
Write-offs (441)
Recoveries (229)
Balance as of December 31, 2020 $ 1,493 

The unbilled receivables balance includes certain costs for work performed at risk but which we believe will be funded by the government totaling approximately $2.6 million and $15.2 million as of December 31, 2020 and 2019, respectively. We expect to invoice substantially all unbilled receivables during 2021.