While I understand you're promoting TurboTax, another reputable tax software reflects a large refund, while turbotax reflects I owe. Why such a difference?

[eastsidr]

There is no way to tell the cause of the large discrepancy without comparing each item that was input into each software product.  The only way to do this is to compare each detailed printout from each software package, including items you input into each package (income, deductions, family components, filing status, tax credits and withholdings, etc).  It is likely there will be one or more items input into one of the packages that is different from the other package.

[SweetieJean]

Be sure you also answered any questions consistency between the two.