Hi Warnie, It was 4.5% bad debt (write-offs) as a percentage of...

Hi Warnie,
It was 4.5% bad debt (write-offs) as a percentage of EOFY gross loan receivables balance. You are quoting percentages of revenue.
Write offs are usually considered from 180+ days in arrears but its not a hard and fast rule. e.g. a client maybe in arrears for say 365 days but are still paying a certain amount every fortnight so MNY may collect the total amount owing over a longer period.
Check out the FY17 annual report (page 35) to get an idea about how much they have been provisioning for receivables in different arrears buckets. Note this methodology is changing this year to an Estimated Loss model.