A Melbourne woman discovered she owed Commonwealth Bank $255 after turning 30 and no longer being exempt from a monthly fee. 

Nikki posted a video on social media on June 17 revealing the conditions of her Everyday Personal Spending Account had changed. 

Commonwealth Bank charges a $4 monthly fee unless customers deposit at least $2,000 a month, are under 30 or qualify for an exemption.

'I have a personal account that I only put money in when I need to spend it,' Nikki said.

'There was about $3 in there. I didn't know when I turned 30, and I forget that I've turned 30 so these rules now apply to me, that if I'm not depositing $2,000 into that bank account each month, I get charged $4.

'Because I only had about $3.05 in there and I was charged $4, I went into the negative [by] 95¢. I haven't had to use the account.'

Nikki said the account had been in the negative since June 1, meaning she had been charged a $15 overdraft fee daily for 17 days. 

'That is $255 in fees I could have avoided by having [an additional] 95¢ in the account,' she said.

Nikki said Commonwealth Bank should email customers before their 30th birthday to warn them their account terms are changing. 

According to the CommBank website, customers can avoid overdraft fees by switching off the overdraft feature.

The Daily Mail contacted the bank for comment. 

In an update, Nikki said she shut her account after discovering the change to her terms and conditions.

'Because I closed the account not long after realising this, and before the system had a chance to charge any positive balance on the account, the $255 in overdraft fees will not be charged,' she said.