6. Current Assets and Current Liabilities

Receivables—Activity in the trade receivables allowance account was as follows for the three-year period ended September 30, 2014.

(in thousands)	Balance at beginning of year		Charged to expense		Accounts written off			Balance at end of year
2012	$	2,938	$	532	$	(1,047	)	$	2,423
2013		2,423		1,302		(948	)		2,777
2014		2,777		2,022		(1,261	)		3,538

In addition to the allowance for trade receivables, in 2013 Headwaters had additional activity of approximately $9.0 million in the allowance account for other receivables, all related to amounts owed to Headwaters by one of the buyers of some of the coal cleaning facilities described in Note 5. This $9.0 million addition represented a 100% reserve on a note receivable and other payments contractually agreed to by the buyer as of September 30, 2013, given the level of uncertainty of collection from the buyer. In 2014, approximately $2.0 million of the $9.0 million receivable was collected, which amount was reflected as gain on disposal from discontinued operations.

Inventories—Inventories consisted of the following at September 30:

(in thousands)	2013		2014
Raw materials	$	9,909	$	12,017
Finished goods		27,474		38,616

	$	37,383	$	50,633

Other Accrued Liabilities—Other accrued liabilities consisted of the following at September 30:

(in thousands)	2013		2014
Products and services received but not yet invoiced	$	24,355	$	19,870
Litigation		16,012		2,795
Other		14,901		19,092

	$	55,268	$	41,757