You are not missing anything. TurboTax is not the only tax preparation software that doesn't support e-filing when the return includes Form 8990, so I'm guessing it's an IRS issue and not a TurboTax issue. If it were me, I would consider omitting the $4 entry and e-file the return. If the IRS sends a letter (they won't) the missing information can be added and Form 8990 mailed to them. I realize it is not the correct way to handle it, and I'm not recommending it. I'm just saying I would consider it.
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