There was a perfectly good answer in https://proconnect.intuit.com/community/lacerte-tax-discussions/discussion/how-to-treat-ss-lump-sum-... Maybe @IntuitBettyJo can get the broken links fixed or point us to how to handle Lump Sum Social Security in PCT. 

You will need to do the worksheets from https://www.irs.gov/publications/p915 (look for the table of contents on the left) and manually attach a pdf and forch the taxable portion of Social Security.