Commonwealth Bank of Australia (ASX:CBA) staff fear homelessness or financial ruin with the bank's "dismal" pay offer, with over 3,000 workers signing a petition calling on Chief Executive Matt Comyn to improve their pay, according to a statement by the Finance Sector Union on Tuesday.

The bank's current offer suggests that roughly 71% of its Australian workforce would see a wage increase below inflation in the first year, while about 47% of employees would receive no guaranteed increase or a total of 2.5% over the next three years, the union said.

The employees are asking for a 5% yearly pay increase and guarantees around job security, workplace flexibility, as well as safe staffing and workloads.

In a statement to MT Newswires, CBA said they have put forward a comprehensive proposal covering pay and other employment conditions, which continues to be negotiated.

CBA shares fell past 1% in morning trade Tuesday.