Retiree couples has only 1099-SSA income under $20,000. Do they need to file?

I'm helping this couples to file tax with only 1099-SSA as income.  The total 1099-SSA income is $20,000, filing married jointly.  When I finished in Turbo Tax, it won't allow me to submit e-file.

 

Base on what I search, they don't need to file tax at all if they don't have any other income.  Is this correct?