While I haven't received any of my tax forms for 2017, I can compute the values for each of the boxes based on past experience and available statements and pay stubs. My tax situation is fairly simple: 1 W-2, 3 1099-INTs, 2 1099-DIVs, and 1 1099-B (the gain was only ~$5). I itemize, only accounting for ~$1000 in charitable donations, which I value myself; property taxes; and mortgage interest. I file married jointly, and I have one young child.
Thus far, I have compared TurboTax, H&R Block, TaxAct, and Credit Karma. Concerning only federal for now, the last three predict the same refund, just above ~$1000, whereas TurboTax predicts a greater refund by $28.
I can't seem to find anything to suggest any input discrepancies between TurboTax and the others. Additionally, from what I can tell, the inputs are pretty straightforward -- no room for different interpretations. Last year, I compared TurboTax and H&R Block, and both returned the same values.
Therefore, my question is whether anyone knows of any subtle difference(s) in how TurboTax computes the refund, relative to other products. If not, I may go through and remove/add different components in an attempt to isolate the culprit.