Commonwealth Bank of Australia Ltd (CBA) has said it is "reviewing its position" after legal challenges left the firm facing the possibility of two separate payments.

CBA, Australia's biggest home lender, said it could have to pay taxes of $NZ285m ($A210m) after a New Zealand court decision on the tax treatment of a number of the bank's transactions. The company has revealed that servicing the payments could lower its Tier 1 capital by as much as six basis points.

In a separate judgement, the lender was ordered to pay a $100,000 fine by the Australian Securities and Investments Commission (ASIC) over its failure to fully disclose loan impairment expenses at the time of a $2 billion share sale late last year.

The Sydney Morning Herald reported that the ASIC criticised the CBA saying it "did not disclose price-sensitive information about the charges as immediately as it should have".

CBA chief executive Ralph Norris expressed his disappointment at the fine, but drew criticism from fund managers by adding that disclosure of bad debts was "not material" to overall profit.