We have been made aware of an issue with filing form UHT-2900 through the Special Elections and Returns (SERs) system. Claiming an exemption in Part 6 and answering Yes to the question at line line 605 triggers error 1720.
The Canada Revenue Agency (CRA) has acknowledged the problem and assured us that they are working on a resolution. However, they have not provided a specific timeline for when this correction will be implemented.