Westpac may need to top up its capital after announcing a big increase in provisions for the March half that will put its capital ratio right on the "unquestionably strong" benchmark.The bank announced yesterday that increased provisions and asset write-downs would add up to around A$1.43 billion after tax for the March half. Included in that amount are $900 million in relation to Austrac's claim over the bank's non-compliance with anti-money laundering law and $130 million for costs associated with its Austrac response plan.The figure of $1.43 billion is before making any impairment provisions, which are expected to include a significant collective provision increase in anticipation of COVID-19 losses.The bank's common equity tier 1 capital ratio was 10.8 per cent at the end of December. In a statement to the ASX it said: "The impact of the items disclosed today on Westpac's CET1 capital ratio is estimated to be around 30 basis points, noting that some items have no impact on capital as they are already capital deductions."APRA's "unquestionably strong" benchmark for the major Australian banks is a CET1 capital ratio of at least 10.5 per cent. The benchmark has been a requirement since January this year.One option for improving its capital position  - a discounted dividend reinvestment plan - is not available since APRA told the banks it wants them to make "prudent reductions in dividends".