If you have formed your company, and registered in your state but not started operating you will need to file a return. You stated 1120 is it a c-corp or an s-corp. Which ever it is just follow Irs instructions for entering expenses for 1120-c, or 1120-s. Here is link: https://www.irs.gov/pub/irs-pdf/i1120.pdf. For startup cost only you will claim in year you start operating.