The applicable rate by reference to which a basic amount of estate income is grossed up for the purposes of sections 656 and 657 depends on the rate at which income tax was borne by the parts of the aggregate income of the estate from which section 679 treats the basic amount as having been paid.

If the same rate was borne by all of the income from which section 679 treats the basic amount as having been paid, the applicable rate is that rate.

If different rates were borne by different parts of the income from which section 679 treats the basic amount as having been paid, each of those rates is the applicable rate by reference to which the corresponding part of the basic amount is grossed up.