If you live in ON you may be subject to the Ontario Health Premium which can not be offset with credits. Review the summary details under the "Provincial" tab. Also review all applicable line items under the detailed federal tax summary.
You can find a detailed summary of your tax return under the "Review" tab > "Bottom Line (tax summaries)"> then look for the paper and magnifying icon in the lower left hand corner, select "Detailed Tax Summary". You will have a line by line sample of the Federal Tax Return.
