Solved
I want to file my son's taxes
When you use Turbotax Online version, you can prepare only one return per account/payment. This Turbotax help topic tells you how to start another return:
https://ttlc.intuit.com/questions/1894512-how-do-i-start-a-second-return-in-turbotax-online
https://ttlc.intuit.com/questions/1894512-how-do-i-start-a-second-return-in-turbotax-online
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