Treat a T3 or a T5 as a 1099-Div or 1099. convert the figures to USdollars if in Canadian and put in the proper place on Schedules B and D.
Calculate the tax you paid to Canada and claim it as a foreign taxcredit on form 1116
There is no reason to fill out a form 8621 or QEF (Qualified ElectingFund) because the Canadian taxes will just about always wipe out anyUS tax by filing form 1116.
You can see Form 8621 here - http://www.irs.gov/pub/irs-pdf/f8621.pdf
Assuming all of your accounts total more than $10,000 US, you will thenfill out forms TDF 90-22.1 for every financial account including RRSP,RRIF and RESP accounts, AND any mother or father or sister or brother'sor company accounts yo may have signing authority over. See Question7 at bottom of Schedule B.
Form TDF 90-22.1 - http://www.irs.gov/pub/irs-pdf/f90221.pdf-
For your RRSP, RRIF and RESP accounts you should file form 3520. Thegood news is that for the RRIF and RRSP accounts you can substitute themuch easier form 8891.
Form 8891 - http://www.irs.gov/pub/irs-pdf/f8891.pdf
The penalties for failure to file these forms are immense.
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This older question explains penalties:
QUESTION:I would like to put some money away for retirement. I'm aU.S. citizen living in Canada for the near future, but I knowI'll be living in the U.S. again before I retire. Should I put my money in an RRSP or an IRA?