Dual citizenship taxation

I have a client, citizen of both US & Canada, with occasional (~ 20%) residence in US and 80% in Canada.

Incomes are (Canada) CPP & OAS and (US) VA disability pension benefit and Social Security benefit.
Would he have to file a return in both countries (as he previously did) or only in Canada.

Both in Canada and US. CPP, OAS AND SS is not taxable in the US, nor is VA disability. VA disability may also not be taxable in Canada.

Thanks Bert, you confirm my findings:
US’ IRS requires tax returns be filed, based on Citizenship rather than Residency for Canada.
However from his 2017 US return (from another firm) his CPP & OAS was included as income …
His US, VA disability pension, would qualify as non-taxable in both countries, which leaves his US’ Social Security income as foreign income in Canada and subject to the post 1996 exemption and his CPP & OAS incomes.
In the US. his SS could be subject to tax implications depending on his total income.
From previous year’s Canadian return, (again, from another firm) his SS was omitted…

As I said, none of his social security income is taxable in the US as he is expat living in Canada, as per the US-Canada tax treaty. This means his OAS, CPP, SS.

See Article XVIII (5)

I stand corrected. :face_with_monocle: