Hopefully you extended your 2015 Rhode Island corporate return that was due on March 15, 2016, because Rhode Island recently adopted final combined reporting regulations with an effective date of March 30, 2016 applying to tax returns filed for tax years beginning on or after January 1, 2015.
You can compare the final regulations to the proposed regulations which I described in a previous post.
Rhode Island has also published a FAQ page on its website which should be helpful in beginning the analysis and application of the regulations.