To some degree we have that already in the tax system with the ability to combine your credits with your spouse, and that tax credit could be taken by either spouse. Typically it would be the spouse who is paying the higher tax bill, although in a lot of cases it won't matter. If one spouse, for instance, is not taxable and the other is, then from a tax perspective it would be the person paying the tax.
In terms of being able to allocate the income, to split income between the two spouses in the couple, I don't know if that would necessarily impact the tax benefits of charitable donations. I say that because our system, at least above the $200, provides the same level of tax credit or tax benefit for any taxpayer, regardless of what income level they are in.