The rule change will come into effect on 1 February 2019, and is one of a package of measures designed to help protect consumers from excessively high energy bills.
Currently, electricity retailers aren't required to inform customers of price changes until their first bill after the change takes effect. This could leave customers paying an unknown electricity rate for up to three months.
The Australian Energy Market Commission says changing the notice period to five business days (for both market and standing offers) will provide greater transparency and more opportunity for customers to manage changes to their energy bill before the new charges occur.
Bruce Mountain, energy economist and director of CME Carbon and Energy Markets says the advance notice may prompt customers to switch retailers, but it doesn't make choosing a better deal or comparing the new rate and its impact on your household budget any easier.
"It's not a hugely meaningful change," he says. "Absolutely, retailers should give notice of price changes before they take effect and it's amazing that some did not before. But will this shake up the retail market? Surely not.
"For customers to test the market they need to work out all the new charges after the price change, including daily charges, usage charges and, if applicable, solar feed-in rates."
As well as receiving notice of the new tariff, customers will also be informed that they can access historical usage and billing data in order to assess the impact of the changes on their bill.
However, being told you can access information isn't the same as simply being given the relevant data in the notification.
"An additional figure which indicates the difference in cost would be a useful aid for customers, and would clearly show the impact of the price change," says Linda Przhedetsky, CHOICE's complex markets campaigner.
The change affects customers in NSW, SA, QLD, TAS and the ACT (unless they're on regulated electricity prices set by government). Victoria has its own Energy Retail Code and Queensland already has a state law that requires retailers to notify customers on market offers at least 10 days in advance of price changes.