NAB's compensation bill for customers affected by years of misconduct has now pushed through $1 billion.

Key points: NAB's bill for compensating customers hit by misconduct has hit $1.1b after another $749 million costs were identified

NAB's bill for compensating customers hit by misconduct has hit $1.1b after another $749 million costs were identified So far only $145 million has been repaid

So far only $145 million has been repaid Additional remediation costs were found in mis-sold consumer credit insurance and poor advice from its wealth business

The bank announced another $749 million in before-tax costs for its customer remediation program flowing from the scandals uncovered at the banking royal commission.

After tax, the charges come in at $525 million, which will be a direct hit to its first-half cash earnings.

So far of the total $1.1 billion set aside for remediation, NAB has paid out just $145 million via 360,000 payments to customers since June last year.

"We are putting things right where we have treated our customers poorly and making sure that they are compensated more quickly," NAB chief executive officer Philip Chronican said.

"There are currently around 350 people dedicated to remediating customers and we will soon have 500 across NAB as we bring greater focus and discipline to resolving issues and making sure they don't happen again."

The new remediation costs centre on a number of sales platforms that drew harsh criticism at the royal commission:

Consumer credit insurance

Consumer credit insurance Non-compliant advice provided to wealth customers

Non-compliant advice provided to wealth customers Adviser fees charged by NAB's salaried advisers

Adviser fees charged by NAB's salaried advisers Adviser fees charged by NAB's self-employed financial advisers

NAB has joined other big banks, CBA and ANZ in selling out of the scandal-prone wealth advice business, citing the need to simplify the bank's operations and get back to its core businesses.

Costs still rising

This is unlikely to be last time a financial institution increases its provisions for remediating misconduct and overcharging customers.

Earlier this year, analysts at Macquarie research estimated the big banks, along with wealth advisors AMP and IOOF, could see their provisions double to $6 billion from the then-estimate of $2.6 billion.

The Macquarie report accurately predicted NAB would need to lift its remediation costs to $1.1 billion.

The forecasts were predicated on remediation costs worked out at around $750,000 per adviser, which was the experience at Westpac.

Given NAB had 1,600 planners on its books, the $1.1 billion in costs so far works out at around $690,000 per adviser.

"It's a long-awaited announcement, but unlikely to be the end of it for either NAB, or the sector," Shaw and Partners' bank analyst Brett le Mesurier said.

"NAB's announcement doesn't include the cost of refunds for aligned advisers, which could be well over $100 million," Mr Le Mesurier said.