Hello Mr. Kotlikoff,
I am receiving CDN$150 CPP. I have applied for the Old Age Security (OAS), too. To get Canadian OAS, I need credits from the US Social Security system (I have 20 years of work on the USA and about 5 in Canada). I am applying for my US Social Security pension now and found out that I may be a subject to WEP due to my CPP, while the WEP does not apply to OAS (residence-based pension). However, it seems that WEP does not apply when US Soc Security credits are used to receive Canadian pension. My question is: "Am I subject to WEP (because of my CPP), if I need US SS credits to qualify for the Canadian OAS pension?"
No. If the only other pension you receive is a totalization benefit based on both U.S. and Canadian credits, then your U.S. Social Security retirement benefit shouldn't be subject to the Windfall Elimination Provision (WEP). The Canadian OAS pension that's based on residence never counts for WEP purposes (https://secure.ssa.gov/apps10/poms.nsf/lnx/0201701320), but the CPP pension that's based on earnings does count for WEP unless you qualify for the CPP as a result of the totalization agreement between the U.S. and Canada. In other words, if the only reason you qualify for a CPP pension is because Canada gave you credits for your U.S. work, then your Canadian pension shouldn't cause a reduction in your U.S. Social Security retirement benefit rate (https://secure.ssa.gov/poms.nsf/lnx/0300605386).