** Jefferies expect some ongoing cost impost for Australia's top supermarket chains Coles COL.AX and Woolworths WOW.AX, including both wage cost and administration expense

** Brokerage estimates the impact to be relatively modest, perhaps A$10 million to A$20 million ($6.59 million to $13.19 million), which would be less than 1% of the firms' EBIT

** WOW and COL said in separate statements on Monday that they could incur millions in additional remediation costs following the federal court's decision on historical underpayments to staff

** Jefferies sees these costs to be one-off in nature for both the companies, given the ability to largely mitigate future impact

** Jefferies expects WOW to incur substantially more impost than COL, with estimated impact of 3.2% of valuation for WOW &

0.7% for COL

** Brokerage also expects further changes, including potential changes in salary payment cycles, by both the firms

** YTD, WOW down 9% and COL up 25.8%

($1 = 1.5165 Australian dollars)

(Reporting by Sherin Sunny in Bengaluru)

((Sherin.Sunny@thomsonreuters.com))