IMO the simple W-2 is not the problem (which is probably why the "partner" got a much cheaper rate).  I would charge a minimum of [looks up the current penalty amount] $635 for the DueDoo related to the EIC and CTC.  If there's a partner instead of a spouse that leads to a whole lot more questions that need to be asked, answered, and documented.  Not to mention copies of any documents "relied upon" in determining the credit.

That said, I'm a little more strict in terms of documentation when it comes to due diligence for first year clients.  In subsequent years I can choose not to rely on documentation by asking a question such as "In $earlieryear you were able to provide documentation supporting the fact that the kids lived with you, would you be able to provide similar documentation if audited by the IRS for $thisyear?"

Rick