If you buy an non cellular iPad can you later add a data plan to it?

If you buy an iPad that is non cellular, you will not be able to add anything to it later. It has no ability to place a SIM card in it so it will always only be WiFi. If you wanted to like stated above you would have to purchase a MiFi or something along that line and create a hotspot for it. I use my iPhone's personal hotspot and connect mine that way. I always have my phone on me so I never have to worry and my hotspot is included in my plan.

Not in and of itself. however you can get something like a Mifi, which is a portable wifi hotspot you can connect to your cellular plan and make a hotspot that you connect the iPad to.

For clarification:

You can buy an iPad Wifi + Cellular, you can do so without activating a data plan with a carrier, and if you want activate it later. This means that the iPad will work off of Wifi until you decide to activate a cellular plan.

If you buy a wifi only iPad, it does not have cellular hardware so cannot be used with a data plan at all later.

Aw schucks Sky you're just too quick for me. I had a link and everything. Oh well, no use letting a good link go to waste. 🙂

https://en.m.wikipedia.org/wiki/MiFi

No because it does not come with the HARDWARE to run on cell data (sim card slot)