Balance at

Additions

Changes to

Balance at

beginning

charged to

reserve, net(1)

end of year

of year

earnings

Year ended December 31, 2017

Allowance for doubtful accounts

$

1,158

$

1,475

$

(1,577)

$

1,056

Valuation of deferred tax assets

640

 -

137

777

Year ended December 31, 2016

Allowance for doubtful accounts

$

1,343

$

208

$

(393)

$

1,158

Valuation of deferred tax assets

 -

(7)

640

Year ended December 31, 2015

Allowance for doubtful accounts

$

1,667

$

305

$

(629)

$

1,343

Valuation of deferred tax assets

 -

(953)

647

(1)

Increases (deductions) from the allowance for doubtful accounts equal accounts receivable written off and increases related to acquired businesses, less recoveries, against the allowance. Increases (deductions) to the valuation of deferred tax assets relate to the reversals due to changes in management’s judgments regarding the future realization of the underlying deferred tax assets.