This excerpt taken from the LTEC 10-K filed Apr 16, 2007.
g) Accounts Receivable
Accounts receivable are recorded at the invoice amount and typically do not bear interest. The allowance for doubtful accounts is our best estimate of the amount of probable credit losses in our existing accounts receivable. We determine the allowance for doubtful accounts based upon our historical write-off experience, the current aging of accounts receivable, and customer specific credit risk factors. Accounts receivable balances are written off when we determine that it is unlikely we will receive future remittances. We do not have any off-balance-sheet credit exposures related to our customers.
Allowances deducted from accounts receivable for the years ended December 31, 2006, 2005, and 2004 are as follows (in thousands):