The company said it was experiencing a systems outage that prevented access both to the client portal and app, as well as client messaging and payments systems.
MyBudget offers debt consolidation services and debt management and also helps people tackle bill payments, bankruptcy and personal insolvency. It has about 13,000 customers.
The site is hosted at Amazon's Sydney data centre and runs on Linux with Apache as the Web server software.
While the obvious conclusion may be that the site was hit by ransomware, no indication has been given by three of the most common of these forms of Windows malware — DoppelPaymer, REvil or Maze — that MyBudget is among its victims.
MyBudget has been providing regular updates about the situation to its customers, including video messages from its founder, Tammy Barton.
In the latest update issued on 13 May, Barton said: "Our tech team is very close to giving us the green light to announce that our systems are back up and running again.
"We are committed to not going back online until we can do so with absolute confidence in the system. I want to say again that your money is completely safe. And in the meantime, we’re still processing payments manually."