Accounts receivable consists of the following:

 

		December 31,
		2016			2017
		RMB			RMB
Accounts receivable:
Gross			214,142			354,057
Unearned interest			(15,130)			(24,544)
Total accounts receivable			199,012			329,513
Less: allowance for doubtful accounts			(100,462)			(98,231)
Accounts receivable, net			98,550			231,282

 

The classification of accounts receivable is as follows:

 

		December 31,
		2016			2017
		RMB			RMB
Accounts receivable, net – current portion			97,374			216,700
Accounts receivable, net – non-current portion			1,176			14,582
Total accounts receivable, net			98,550			231,282

The movements of the allowance for doubtful accounts are as follows:

 

		Year Ended December 31,
		2015			2016			2017
		RMB			RMB			RMB
Balance at the beginning of the year			35,347			66,857			100,462
Additions charged to bad debt expense			63,103			33,605			31,499
Write-off of bad debt allowance			(31,593)			-			(33,730)
Balance at the end of the year			66,857			100,462			98,231

The aging analysis of our accounts receivable based on due date is as follows:

 

		As of December 31,
		2016			2017
		RMB			RMB
Aging:
– current			78,276			130,551
– 1-3 months past due			15,306			96,307
– 4-6 months past due			10,846			19,861
– 7-12 months past due			22,748			13,741
– greater than one year past due			71,836			69,053
Total accounts receivable			199,012			329,513