If you need to mention the total balance in the customer's currency of all the invoices overdue by X days, or between X and Y days, this guide explains how.
Let's imagine this scenario:
The customer currency is USD
They have 3 invoices:
USD 99 overdue by 5 days
USD 5 overdue by 10 days
USD 3 overdue by 12 days
MORE THAN X DAYS
You can write in your template:
The balance 10 days and over is:
{{ customer.currency.iso }} {% balance_overdue_more_than_days customer 10 %}
It will output:
The balance 10 days and over is: USD 8.00
BETWEEN X AND Y DAYS (range)
If instead you want a range, you can write in your template:
The balance overdue between 5 and 10 days is:
{{ customer.currency.iso }} {% balance_overdue_between_days customer 5 10 %}
It will output:
The balance overdue between 5 and 10 days is: USD 104.00