My mother received a retroactive distribution from a private Canadian pension plan (my father's). How do I report the amounts attributable to prior years?
If you are completing a US tax return, you will actually report the entire amount in the tax year received. If you are completing a Candian tax return then you will need to post your question on the Canadian AXC site: https://turbotax.community.intuit.ca/tax-help
In the United States, when a taxpayer receives retroactive Social Security payments, the lump sum benefit can be apportioned to prior tax years, which may help reduce taxable Social Security income. However, this option is not available for private pensions or foreign pensions.