An executor would generally check personal papers to see if the deceased left accounts with certain banks, or owned certain property. They could also speak to the person's accountant or lawyer to understand what was owned.
Additionally, the executor can use the Australian Death Notification Service to notify various organisations about the person's passing. Those organisations would be in touch if the person held accounts with them.
For liabilities, the executor would generally write to energy and water providers and telecoms to see if the deceased had an account.
Understandably, this process can be time consuming for your executor. For that reason, we have created the Safewill Digital Vault, giving you the ability to securely store all the information your executor will eventually need, including your service providers, subscriptions, key contacts and details of your assets and liabilities. This should significantly reduce the cost and effort required to administer your estate when the time comes.