The following tables summarize activity in each of the net product revenue allowance and reserve categories described above for the three months ended March 31, 2018 and 2017:

In thousands	Trade Allowances			Rebates, Chargebacks and Discounts			Product Returns			Other Incentives			Total
Balance as of December 31, 2017	$	12,035		$	32,064		$	1,887		$	2,107		$	48,093
Provision related to current period sales		8,506			32,947			222			4,185			45,860
Provision related to prior period sales		(200	)		(435	)		—			(69	)		(704	)
Credits/payments made for current period sales		(875	)		(10,487	)		—			(1,799	)		(13,161	)
Credits/payments made for prior period sales		(1,336	)		(20,994	)		(25	)		(2,296	)		(24,651	)
Balance as of March 31, 2018	$	18,130		$	33,095		$	2,084		$	2,128		$	55,437

In thousands	Trade Allowances			Rebates, Chargebacks and Discounts			Product Returns			Other Incentives			Total
Balance as of December 31, 2016	$	3,743		$	20,915		$	859		$	1,681		$	27,198
Provision related to current period sales		6,621			19,670			1,028			3,107			30,426
Provision related to prior period sales		(298	)		(702	)		—			(82	)		(1,082	)
Credits/payments made for current period sales		(2,357	)		(727	)		—			(1,332	)		(4,416	)
Credits/payments made for prior period sales		(3,107	)		(15,376	)		(9	)		(1,770	)		(20,262	)
Balance as of March 31, 2017	$	4,602		$	23,780		$	1,878		$	1,604		$	31,864