Other Current Liabilities

9 Months Ended

Sep. 27, 2019

Accrued Liabilities, Current [Abstract]

Components of other current liabilities were (in thousands):



	September 27, 2019		December 28, 2018
Accrued self-insurance retentions	$	8,337	$	7,870
Accrued warranty and service liabilities	12,222		11,056
Accrued trade promotions	7,954		11,449
Payable for employee stock purchases	10,123		11,916
Customer advances and deferred revenue	46,693		39,995
Income taxes payable	8,939		8,515
Right of return refund liability	13,293		12,705
Operating lease liability, current	7,906		—
Other	35,978		39,535
Total	$	151,445	$	143,041

A liability is established for estimated future warranty and service claims that relate to current and prior period sales. The Company estimates warranty costs based on historical claim experience and other factors including evaluating specific product warranty issues. Following is a summary of activity in accrued warranty and service liabilities (in thousands):



Balance, December 28, 2018	$	11,056
Charged to expense	7,781
Margin on parts sales reversed	2,096
Reductions for claims settled	(8,711		)
Balance, September 27, 2019	$	12,222

Deferred Revenues

For certain products or services and customer types, we require payment before delivery to the customer. We defer revenue when cash payments are received or due in advance of our performance, including amounts which are refundable. This is also the case for services associated with certain product sales. The balance in the deferred revenue and customer advances was $46.7 million as of September 27, 2019 and $40.0 million as of December 28, 2018. Net sales for the year to date included $34.9 million in 2019 and $21.8 million in 2018 that related to deferred revenue as of the beginning of each period.