BHP Billiton Ltd has declined to reveal the total effective tax it will pay under the Gillard government's mineral resource rent tax, according to The Australian.

The global miner had previously stated the original resource super-profits tax would see its effective tax rate climb to 57 per cent, from 43 per cent currently.

While analysts predict the MRRT will see mining companies paying a total effective tax rate of 35 to 44 per cent, the Minerals Council of Australia yesterday said it will not release any tax rate approximates before the MRRT deal has been completed.

BHP Billiton chairman Jac Nasser earlier this week said the MRRT was a "good foundation" but still needed detailed work before implementation.

"We will work with the government to ensure that the final outcome of the minerals taxation proposal maintains the international competitiveness of the Australian resources industry and is in the long term interests of all Australians," according to his letter to shareholders.

Moody's Investors Service has said the revamped tax deal is not likely to cause "undue negative impact" for the miner.

"For a company like BHP Billiton, the new tax not only reduces the tax burden on its coal and iron ore operations (relative to RSPT), it also exempts other products, such as nickel and copper, which would have been captured under the RSPT," Moody's said in a statement.