When your account lacks sufficient credits to send a fax, you have the option to purchase additional credits. The minimum amount you can add is $8.99. These credits do not expire and will roll over from one month to the next.
The cost of sending an additional page varies based on your subscription plan. For the Free plan, it's $0.20 per page; for Basic, $0.10; for Premium, $0.07; for Business, $0.05; and for Enterprise plans, it's $0.03 per page. This tiered pricing structure allows you to choose a plan that best suits your faxing needs.
Tip: You can find more information on how to add credits to your account by referring to this article.