# How Practice CS calculates service charges

For each invoice, Practice CS divides the amount subject to service charges by 365 days, and multiplies that by the annual percentage rate (APR) entered in the Service Charges setup screen, to determine a daily rate. Then it multiplies the daily rate by the number of days old to calculate the total service charge.

When calculating the first service charge on an invoice, Practice CS uses the number of days since the invoice date, due date, or due date + grace days, depending on what you select in the Service Charges setup screen. Practice CS begins calculating the service charge on the due date + the number of grace days. For example, if the number of days until an invoice is due is 30, and you have allowed 30 grace days, Practice CS will calculate a service charge 61 days after the invoice date. If the number of days until an invoice is due is 30, and the number of grace days is 0, Practice CS will calculate a service charge 31 days after the invoice date.

Subsequent service charges are based on the number of days since the last service charge was assessed on the invoice.

Example: Not compounded

You send an invoice to a client for \$730 dated March 31. The invoice is due on April 30. On May 31, you assess service charges and send a statement. Your annual percentage rate is 18%.

The daily service charge rate is calculated by dividing \$730 by 365 days, and multiplying that amount (\$2) by 18%. The result is a daily rate of \$0.36. When you send a statement on May 31, the invoice is 61 days old. Multiply 61 days by \$0.36 per day, and the service charge is \$21.96. The total amount due is then \$730.00 plus \$21.96, or \$751.96.

If you send another statement on June 30, the same daily service charge rate is used to calculate the service charges for the month of June. \$10.80 (30 days x \$0.36 per day) is added to the amount due previously.

Invoice amount
3/31
Daily rate Service charge
in May
Amount due
on 5/31 statement
Service charge
in June
(Not compounded)
Amount due
on 6/30 statement
\$730.00 \$0.36 \$21.96 \$751.96 \$10.80 \$762.96

Example: Compounded

If you choose to use compounded interest, the daily rate for the June 30 statement will be higher than the daily rate for the May 31 statement, because it will be calculated based on the new balance due of \$751.96, rather than the original invoice amount of \$730. The new daily service charge rate is calculated by dividing \$751.96 by 365 days, and multiplying that amount (\$2.06) by 18%. The result is a new daily rate of \$0.3708. Multiply 30 days by \$0.3708 per day, and the June service charge is \$11.12. The total due on the June 30 statement is \$763.08.

Invoice amount
3/31
May daily rate Service charge
in May
Amount due on
5/31 statement
June daily rate Service charge
in June (Compounded)
Amount due on
6/30 statement
\$730.00 \$0.36 \$21.96 \$751.96 \$0.3708 \$11.12 \$763.08