It is important to pay the correct postage when sending your mail
Australia Post offers several ways for you to post your mail, including through red street posting boxes conveniently located throughout Australia.
When using red street posting boxes, it is the responsibility of the sender to apply the correct postage for their items before posting them.
Please read our postage guide to learn how your item’s length, width, thickness, and weight affect the total postage cost.
Where an item’s dimensions, weight or thickness are outside what is allowable for a letter, it must be charged as a parcel.
Will my mail still be delivered if I incorrectly calculate my postage?
Australia Post can carry an item with insufficient postage that was lodged in a red street posting box, and then issue an Underpaid Mail invoice to the sender to claim the amount of the deficient postage plus a service fee.
We may also decide to take other actions depending on the circumstances, such as withholding the item for delivery until the deficient postage is paid or seeking payment from the addressee when a sender is not identified.
Where we take such actions, we will communicate this directly.
You can read more about recovery of postage on underpaid items under Section 28 of the Australia Post Terms and Conditions (PDF 725kB).
You received an Underpaid Mail invoice because your mail item/s had insufficient postage.
Your invoice will tell you the number of underpaid items that were detected (“Qty”), how much postage was paid (“Postage Paid”), how much postage should have been paid (“Correct Postage”), the amount owing per item (“Deficiency”), the service fee payable (“Admin Fee”), and a total (“Amount Due inc. GST”).
This information should help you identify any postage calculation errors so you can apply correct postage in the future.
For more help assessing the correct postage to pay, please see our handy guide.
As part of our compliance checking, your mail was detected as being underpaid. Our classification of mail has not changed, and it is likely that your previous mailings were not detected.
Please ensure you review the correct postage for any future items you are sending to avoid receiving future invoices for underpaid mail.
Please read our postage guide to learn how your item’s length, width, thickness, and weight affect the total postage cost. Where an item’s dimensions, weight or thickness are outside what is allowable for a letter, it must be charged as a parcel.
If you require additional assistance or advice, our friendly team at your local Post Office can help you understand measurements and sizing for correct postage calculation.
Under Section 28 of the Terms and Conditions (PDF 725kB), a service fee is payable in addition to the underpaid amount where actions to manage underpaid mail have been required.
Australia Post sets and publishes the Underpaid Mail service fee in its Post charges guide, and provides a summary total of these charges on your invoice as “Admin Fee”.
To avoid this charge in future, please ensure correct postage is paid before posting.
The majority of our business bulk mail services, such as Imprint Mail, Pre-sort Mail, Unaddressed Mail (and others) cannot be lodged in a street posting box and must be lodged over the counter.
Please see your service agreement terms for your individual lodgement obligations or contact our team on the details below if you require further information.
If you have inadvertently lodged such mail, please call our Business Support Team on 13 11 18 Mon-Fri (excluding national public holidays) from 8am-6pm AEST.
If you would like to explore our range of business bulk mail services, please visit our bulk mail services guide.
Before disputing your invoice, please read the postage guide; postage for sending a letter is determined by size, thickness and weight – items that exceed letter maximums must be sent as a parcel.
If you feel you’ve been invoiced incorrectly, please complete an enquiry form on our support page, making sure to describe the details of your invoice, including the Date of Issue and Billing Number, along with the details of your query. One of our helpful team members will investigate and assist you.
Information on how to pay is provided on your invoice, including by Post BillPay (online or in store), or at any Australia Post Office.
If you are a business customer, you may add the invoice to your Australia Post Business Credit Account if you have one, by completing the Business Credit Account portion of the invoice and returning it to Australia Post.
If you would like more information about establishing an Australia Post Business Credit Account, please see our information page here.