Westpac & Income Calculations for serviceability

Had a conversation with a lending manager at Westpac recently and when discussing the issue of serviceability, I was told the following…

They were calculating my serviceability and specifically with my income as net after tax income )which is being paid into my Westpac account) and then subtracting the figure provided by the Henderson Poverty Line for a single with no dependents.

I then asked if I submit a tax variation form, which would effectively increase my after tax income, based on his methodology, this would able me to better my serviceability. He said yes it would improve it.

I always thought that gross earnings were used to calculate serviceability. I made the point to the Lending Manager but he insisted this was the way they calculate serviceability. Not that I will be complaining if true..

Has anyone had a similar experience where their serviceability has increased because of a tax variation?

To the learned the mortgage brokers, is this really true? Or is it because I am a longstanding customer of the bank? I still am not convinced that this advice is correct despite being told…