What is treatment of specific allowance for receivables

It is quite prudent to make an allowance
In the accounts for uncollected receivables.
Based on the experience of the business,
A percentage of receivables should be allocated to a special provision.
Outright bad debts should be written off.
This should be reviewed on a month by month basis.
The bridging of month to month receivable lists should be transparent at all times.

Right...

Many methods for estimating there is no one right answer, acceptable methods can vary depending on business and industry.

Basically what you are trying to do is determine how much of the receivables on the books will eventually prove to be uncollectible.