TurboTax only allows me to enter the net amount withdrawn and amount taxable. Given that I've already paid 25% to Canada, how do I calculate the amount taxable by the US? Or do I declare the gross amount in USD, and then under form 8960 Part II b) then declare the amount of foreign tax paid in USD, and if so, how to I tie the two figures together?
You report the pension plan distribution and then work through the Foreign Taxes section to see if you qualify for a foreign tax deduction or credit. You do this is the Estimates and Other Taxes paid section in the Deductions and Credits area of TurboTax, then choose Foreign Taxes to assign your foreign income to a country and enter the tax paid. To the extent you have US taxes on your foreign income, you will get a credit for those taxes on your US tax return. You can take a deduction or credit for your foreign taxes paid or accrued on income, the credit is normally better.
Thanks, but just so I'm super clear on this, the RRSP withdrawal should be reported under "Personal Income: Canadian Retirement Summary" (or a "mock" 1099-R? or ....?) with 100% being taxable, then, use the Foreign Taxes paid to report the 25% tax withholding by Canada?
No. Report this as a Canadian Registered Pension listed under Retirement plans and Social Security. Then claim a foreign tax credit on the taxes you paid in Canada.