Scenario #1 - you start with a pie. You give some away. Then you give it all away. Then someone comes along and asks for some. They don't care that you gave it all away already. They want some. You scrape the pie pan and give them some. This continues to happen until it feels like you gave 2 pies away.
Scenario #2 - you start with a pie. You give some away. Then you give what you think is all of it, but somehow you end up with 2 pieces left. No one comes calling. You have pie leftover.
Both scenarios can happen to a company when filing state income tax returns due to the lack of uniformity among states in filing methodologies, income sourcing, and apportionment methods. This year, states are passing legislation that is not only responding to federal tax reform, but also changing each of these areas for some states.
Companies should monitor state tax legislation and model out the changes to determine how their income tax liability will shift from state to state.
The question is - will you have pie leftover or will it feel like you have given 2 pies away when you only had one to begin with?