A taxi company has been charged over the deaths of two passengers whose wheelchairs tipped backwards during separate incidents in northern Victoria.

Echuca-Moama Taxi Group is facing four charges brought by WorkSafe of failing to ensure people other than employees were not exposed to heath and safety risks.

A 63-year-old woman died after her wheelchair fell backwards during a journey in Echuca on February 6, 2021.

A 75-year-old man suffered a fractured sternum on June 28 that year after his chair tipped backwards.

He died from complications while being treated in hospital a week later.

The workplace health and safety regulator alleges the company failed to maintain a safe system of work or train drivers how to use the wheelchair tie-down system in line with manufacturer's guidelines.