Yea I'm not so sure about TeamViewer. I tried setting up nomachine on my parents laptops to help them with computer issues but for some reason it couldn't configure their router on its own to access over the Internet. TeamViewer had no issues doing that. That's when I decided to buy them a $10 router from Craigslist, install dd-wrt and set it up as a VPN server. The tax document transfer in my case is just a bonus for using a secure VPN. For minor computer issues in the mean time I'll still use TeamViewer just because it's working.