How to enter Canada NR4 (Income code 11) with Exemption Code S into US tax return?

Enter your Canada NR4 (Income code 11) income in the section for US Social Security.

On sidebar 

1. Select Federal 
2. Wages & Income 
3. Select Wages and Salaries, or Revisit 
4. Scroll to Retirement Plans and Social Security
5. Select the type of income
   1. IRA, 401(k), Pension Plan Withdrawals (1099-R)
   2. Social Security (SSA-1099, RRB-1099)
   3. Canadian Registered Pension Income
6. Enter as if the NR4 was Social Security.

Note: All amounts must be in US Dollars.

Enter taxes paid to Canada under Foreign tax credits.

To get to the Foreign Tax Credit

1. Go to Deductions & Credits
2. Estimates and other taxes paid.
3. Select Foreign Tax Credit.

This is a lengthy interview, but it does work.

An “S” exemption code is entered in box 18 or 28 of the NR4 slip to report that there is no withholding tax.  This does not mean you do not owe US tax.

Where do I enter the foreign tax credit (Form 1116) or deduction?

Yes, you should enter your Canada NR4 Form as follows:

Enter your Canada NR4 (Income code 11) income in the section for US Social Security.

• Enter it in the Retirement Plans and Social Security section, under ‘Social Security (SSA-1099, RRB-1099)’.
• Search (upper right of program) 'ssa-1099' and click the 'Jump to' link from results
• Answer Yes to Did you receive any Social Security benefits?
• Check the box for Social Security benefits (Form SSA-1099) and enter the amounts from NR-4

Enter your withholding as a foreign tax credit or deduction.

1. Type foreign tax credit in Search in the top right
2. Select Jump to foreign tax credit

Click here for additional information regarding entering the Foreign Tax Credit.

I'm not an expert, but I also had an NR4 with code 11. I think how you handle it for US taxes depends on the item that generated the income. If it's a non-RRSP mutual fund then it's treated as a PFIC and then reporting it can get a lot more complicated.