You will see the following error message in H&R Block’s 2017 tax software if you indicated on the T1212: Statement of Deferred Security Options Benefits page that you had benefits that can no longer be deferred in the year but did not complete the related section on the Schedule 3: Capital gains (or losses) in 2017 page:

You need to complete the Publicly traded shares, mutual fund units, deferral of eligible small business corporation shares, and other shares section in the Schedule 3 because you entered benefits that can no longer be deferred (in the T1212 form). [error code: 188]

How do I fix this? 

To fix this error, on the Schedule 3 page, select Publicly traded shares, mutual fund units, deferral of eligible small business corporation shares, and other shares from the list of capital properties you want to report on. Enter the details of the shares or mutual funds you disposed during the year.

Note: The Schedule 3 page can be found under the PENSION PLAN AND INVESTMENTS icon of the PREPARE tab and the T1212 page can be found under the EMPLOYMENT icon of the PREPARE tab.