Australian miner Macarthur Coal has rejected Peabody‘s takeover bid as too low.

The bid has been reduced from A$4.1bn ($3.6bn) to A$3.8bn ($3.4bn) following the Australian Government’s proposal to impose a 40% tax on the profits earned by mining firms from 2012, as part of a wider review of its tax policy.

MacArthur had already rejected Peabody’s first two offers and advances from Australia’s New Hope.

Shares in Macarthur fell by 15% on Tuesday, close to levels seen before Peabody’s first bid.