@username3000 I did the "fill IRS paper work-sheet and form" vs "follow TurboTax step-by-step instructions myself". Result: If you follow the steps (fill-in the worksheets) in the IRS Publication you can get to a significantly different tax-to-be-paid result for Form 8615, than if you follow the TT step-by-step. In my particular case, the correct tax was over 25% lower than what TT had suggested vis step-by-step. - -So it might be worth while to force TT to yield the correct result.
Here is how:
Background:
The step-by-step process only asks for the parent's income. That leaves essential information blank on Form 8615 that impacts the final tax calculated, including whether the parents had long-term or short-term capital gains/losses on their Schedule D, if they had qualified dividend payments, if the child for which 8615 is summitted had siblings by the same parents for which 8615 is submitted, too. Whether those siblings had capital gains, qualified dividends, etc.
Fix:
What you do is to EXIT Step-By-Step when it asks you to (only) enter the parents taxable income and move to FORM mode (that only works if you have the TT desktop program). There you fill in form 8615 and the multiple worksheets that will be generated as you do so, manually. Mainly with the information I list above. To be able to provide the info on the other siblings (if any) you need to have prepared their taxes up to form 8615, as well to have their numbers be calculated as well and finally put into each others forms.
Once you are in Form mode, you will understand what I mean.
It's easy to file a wrong return following TT step-by-step and fixing it with the program is quite convoluted (probably takes an extra 15-30 minutes per child), but you will notice that is the case for many tax areas that are not very commonly used once you use the program a bit.
