The move is to boost its reserves as a buffer against a potential downturn in the UK economy while bank regulators look to higher levels of capital.
NAB, which also owns Yorkshire Bank, said it was allocating the money to its Clydesdale subsidiary from its own capital reserves.
It is understood core tier 1 funding has now risen to about 11% of the Glasgow-based bank’s balance sheet.
David Thorburn, chief executive at Clydedale, said: “This capital increase continues our focus on maintaining a conservative level of liquidity and strong capital ratios.”
