Ask HN: How does your SaaS product handle sales tax?

I'm a one-man startup building a SaaS product for my LLC in Wisconsin, and I'm fumbling around with how to handle sales tax for the subscription based model. Being a SaaS product, there is nothing "tangible" to it and it's kind of treated like a service, so a majority of states will not require you to charge sales tax. But some do.

It seems like WI doesn't charge a sales tax on SaaS products for the time being (https://www.revenue.wi.gov/Pages/FAQS/pcs-computera.aspx). However, this may change at some point, and more concerning is I believe there are some states that require the purchaser/customer to pay sales tax for the service, because _their_ state demands it.

Ironically, there's some SaaS companies that handle some of this sales tax handling for you, such as Avalara (http://developer.avalara.com). I've seen other people mention that they're only concerned about their company's nexus (i.e. where they do-business, for me, that'd be WI), and that they'll just deal with any nuanced sales tax laws in an audit if the time ever comes.

Doing some googling around, I think it's clear that the tax system hasn't caught up with the movement to SaaS.

I'm skeptical about integrating with another product on top of my card processor that will "handle" this for me, because to me it's just another point of failure, and I'd like to know what's going on. On the other hand, I'm paranoid that I could get into some legal trouble, and now would be the time to flesh some of this out (before beta).

What have you or your company done to handle sales tax for your SaaS product(s)?

Here's some Q&A I found online that ask similar questions. - https://www.proformative.com/questions/sales-tax-saas-subscriptions-sofware - https://trustfile.avalara.com/blog/5-steps-to-determine-sales-and-use-tax-on-saas-subscriptions/ - http://blog.indinero.com/saas-business-state-sales-tax