Thanks for the tip @Fletch44 , I took your advice and switched to Chrome for pdf viewing in windows system settings> choose a default app for file types. Once you do this, your print tests from QB will open in chrome. When printing from chrome, you'll get a chrome print dialog box. What worked for me was to click >more settings>scale>custom. After messing around, I settled on 102% scale, then adjusted alignment in QB up 8 points. That printed everything in the bounds of the boxes on printed W-2s. 

Based on what's in this string of posts, different printers must parse the pdfs differently. I'm using a Brother inkjet.  

Great way to spend an afternoon, thanks Intuit!