3.	Accounts receivable

Approximately 12% and 14% of the Company’s accounts receivable balances as of December 31, 2014 and 2013, respectively, were more than six months old, and there were no significant balances over one year old. Accounts receivable are principally from Medicare and Medicaid programs and commercial insurance plans.

Accounts receivable are reduced by an allowance for doubtful accounts. In evaluating the ultimate collectability of its accounts receivable, the Company analyzes its historical cash collection experience and trends for each of its government payors and commercial payors to estimate the adequacy of the allowance for doubtful accounts and the amount of the provision for uncollectible accounts. Management regularly updates its analysis based upon the most recent information available to it to determine its current provision for uncollectible accounts and the adequacy of its allowance for doubtful accounts. For receivables associated with dialysis patient services covered by government payors, like Medicare, the Company receives 80% of the payment directly from Medicare as established under the government’s bundled payment system and determines an appropriate allowance for doubtful accounts and provision for uncollectible accounts on the remaining balance due depending upon the Company’s estimate of the amounts ultimately collectible from other secondary coverage sources or from the patients. For receivables associated with services to patients covered by commercial payors that are either based upon contractual terms or for non-contracted health plan coverage, the Company provides an allowance for doubtful accounts by recording a provision for uncollectible accounts based upon its historical collection experience, potential inefficiencies in its billing processes and for which collectability is determined to be unlikely. Approximately 1% of the Company’s net accounts receivable are associated with patient pay and it is the Company’s policy to reserve 100% of the outstanding accounts receivable balances for dialysis services when those amounts due are outstanding for more than four months.

During the year ended December 31, 2014, the Company’s allowance for doubtful accounts increased by $5,531. The increase in 2014 was primarily due to an increase in the provision for uncollectible accounts due to an increase in the write-offs of Medicare secondary billings. During the year ended December 31, 2013, the Company’s allowance for doubtful accounts decreased by $7,979. The decrease in 2013 was primarily due to an increase in the timing of non-covered Medicare write-offs during the period in the Company’s U.S. dialysis business. There were no unusual non-acquisition transactions impacting the allowance for doubtful accounts.