National Australia Bank has reclaimed the mantle of Australia's largest destination for corporate and business deposits after Commonwealth Bank suffered a net outflow of deposits from business customers in September.Official data published on Tuesday by the Australian Prudential Regulation Authority show NAB had A$112.8 billion of business deposits on its books at the end of September compared to $107.3 billion for CBA.While NAB, ANZ and Westpac all managed to grow their stockpiles of deposits from non-financial companies in September, CBA experienced a net decline of more than $3.4 billion.The major banks have been locked in an intense battle for business deposits for several years, which has resulted in NAB, Westpac and CBA vying for market leadership.CBA's stranglehold on the retail deposits market is slowly loosening, according to APRA's latest monthly banking statistics.CBA grew its household deposits base by only $893 million or 0.36 per cent in September, which was well below the system growth rate of 0.84 per cent.The fastest growing retail deposit taker among the major banks this year has been ANZ.In September ANZ expanded its retail deposits by $1.3 billion or 1.12 per cent to $116.7 million.Westpac, which has grown household deposits slower than ANZ for most of this year, had a bumper month hauling in $2.3 billion in new deposits from households. The bank now has a retail base of $202.7 million.NAB now has $123 billion of household deposits in its care after raking in an extra $1.1 billion in September.Almost every bank in the country managed to increase retail deposits during the month, although Auswide Bank suffered a decline of $13 million to $1.71 billion.