National Australia Bank's full-year cash profit has tumbled 37 per cent to $3.7 billion on the back of higher costs, more remediation charges and another $1.028 billion in provisions, as it braces for the full impact of the virus crisis.

"The challenges of the operating environment are evident in today's results," CEO Ross McEwan said on a media call. He pointed to the large provisions, along with "revenue headwinds from low interest rates, and subdued credit demand" hitting earnings, which fell in-line with expectations.