Balance at
Beginning of
Year

Additions

Deductions/
Write offs

Balance at End of Year

Year Ended December 31, 2020

Allowance for doubtful accounts for trade receivables and contract assets

$

3,210

3,282

(1,606)

$

4,886

Valuation allowance on deferred tax assets

$

3,877

1,608

—

$

5,485

Year Ended December 31, 2019

Allowance for doubtful accounts for trade receivables and contract assets

$

1,557

2,072

(419)

$

3,210

Valuation allowance on deferred tax assets

$

3,189

688

—

$

3,877

Year Ended December 31, 2018

Allowance for doubtful accounts for trade receivables and contract assets

$

1,186

2,722

(2,351)

$

1,557

Valuation allowance on deferred tax assets

$

924

2,265

—

$

3,189