You need to be able to measure your solar project’s progress in order to qualify for the different ITC deadlines. Your eligibility is determined by two main tests: the Physical Work Test and the Five Percent Test. For the Physical Work Test, you must provide proof that your project’s construction began before the deadline you want to meet. So if you want the 26% tax credit, you must offer proof that your project’s construction began before 12/31/2020. For the Five Percent Test, you must offer proof that you incurred 5% of the project costs by the project deadline, such as 12/31/2020. These costs can include permits, plans, and site assessments, among other aspects of the project. If you meet the requirements of the Physical Work Test or the Five Percent Test by 12/31/2020, you will receive the 26% tax credit.