I am trying to locate the Underused Housing Tax form UHT2900 in turbotax. Is it included or does it still need to be updated and added.

This form is not included in TurboTax. You can download the form from the Canada Revenue Agency (CRA)’s website: https://www.canada.ca/en/revenue-agency/services/forms-publications/forms/uht-2900.html

This CRA page has more information on the Underused Housing Tax: https://www.canada.ca/en/revenue-agency/services/forms-publications/publications/uhtn3/filing-return-paying-underused-housing-tax.html