A $15000 distribution, in the 15% tax bracket would result in a tax of $2,250, If your bracket is higher, your tax is still higher. The factor generated by your total IRA value is only helping you not hurting you, since your basis reduction is not taxable.
Your IRA and his are treated separately, for purposes of Form 8606, and your distribution, include only your own IRAs.
That's one of the "surprises" for IRA retirees, the taxes are high !
