Thanks for your response.
Turbo Tax did not generate a Schedule 3 for me so Line 18d on my 1040 is blank.
Turbo Tax would not let me preview my forms until after I paid the fee. So, I paid the fee and see that Turbo Tax did in fact generate form 1116 along with the supporting Foreign Tax Credit statements.
The fact that Turbo Tax seems to think that I haven't started (let alone completed) the Foreign Tax section while at the same time generating the Foreign Tax forms tells me that there is a bug in the system. I don't know if Turbo Tax should have generated a Schedule 3 for me, or if having Form 1116 is sufficient.
