In the Social Security section for entering a SSA-1099 there was a section that asked if you lived in any of the foreign countries listed. If you indicated Yes then the SS benefits would not be taxed. Go back and amend your tax return so that you select No.
See this TurboTax support FAQ for amending a current year tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-federal-tax-return-curr...
To enter Social Security benefits reported on form SSA-1099
Click on Federal Taxes (Personal using Home and Business)
Click on Wages and Income (Personal Income using Home and Business)
Click on I'll choose what I work on (if shown)
Scroll down to Retirement Plans and Social Security
On Social Security (SSA-1099, RRB-1099), click the start or update button
