[hga]

Here's some US individual state tax experiences, granted, all for simple filings, that might suggest some good things:

First state tax return I filled out was in Massachusetts in 1981, and it was the ultimate EZ form: they sent me a punch card with e.g. my ID info already punched into it, and I filled out a few items and was done.

Much more recently Virginia created a very nice web site; they also quite intelligently have a deadline of May 1 so you don't treat your state taxes as something of an afterthought.

Missouri, where I retired to, did a very interesting thing: PDF tax forms which you fill out, hit a button on them I think, and it encoded all the info in a 2D barcode in upper right of the form. Which if all goes well, makes it super easy for them to get everything correctly into their systems.