States have to provide sellers and software providers with 90 days notice of any changes to their tax rate, then update both their database and their software f

States have to provide sellers and software providers with 90 days notice of any changes to their tax rate, then update both their database and their software for computing taxes. This, coupled with the state-wide sales and use tax harmonization requirements (for remote sellers), only local businesses will have to worry about things like "tax free weekends" and short-notice changes. It's still going to be a mess.