NIU’s overall budget process includes both external and internal budget processes. A good overview of the budget process and timeline can be found at the Office of Budget and Planning website.
Individual colleges usually have their own budgeting process and timelines that conform to university’s budget process and chairs must familiarize themselves with these with the help of the Business Manager of the college/department, as appropriate.
NIU’s fiscal year cycle is from July 1 of one year to June 30th of the following year. The following website clarifies a number of budget development-related FAQ's.