"Whilst banks appear in good shape today, it's their consumer credit customers who are in bad shape today which the banks may soon reflect."

Under his numbers, Westpac would suffer the most damage, taking a 65 per cent hit to pre-COVID-19 bank profits. CBA would follow with a 48 per cent hit, ANZ with a 44 per cent hit and business bank NAB hurt the least with a 25 per cent charge.

The dire forecast arrives hard on the heels of modelling from the Grattan Institute that shows as many as 3.4 million workers may be out of a job as the impact of the coronavirus wreaks havoc on the economy.

ANZ, NAB and Westpac are due to report interim results between April 30 and May 7.

The banking regulator has ordered the banks to materially reduce dividends or defer them entirely until they can make a reasonable assumption as to the impact of the COVID-19 virus crisis on their capital levels.

Earlier on Monday, NAB revealed its first half profit would take a $1.1 billion hit even before the cost of COVID-19 is counted, citing additional customer compensation charges and the falling value of its wealth business. NAB shares fell 11.5c, or 0.7 per cent, to $16.27 by 10.30am.

NAB's confession that profits would be about 8 per cent lower than forecast followed a similar announcement from Westpac last week, when the bank said its profits would be $1.4 billion lower before the crisis calculations could be taken into account.

The vast bulk of the $1.4 billion hit to profits were costs associated with the allegations it breached anti-money laundering laws 53 million times by financial intelligence regulator AUSTRAC.

UBS analyst Jonathan Mott said Westpac's provisions for COVID-19 could be as much as $1.25 billion or roughly match the original downgrade made last week. Westpac promised to update the market of its estimates before releasing results on Monday, May 4.