You can file a return to officially put on paper that you have no income. It's not required, and you can't e-file unless you have at least one dollar of gross taxable income.
You are required to file if you have more than $400 of income from self-employment, or more than $13,000 of other taxable income. There are a few other wrinkles -- for example, if you are married filing separately, you must file if your spouse files and you have more than $5 of income.
There is an IRS web site to help you determine if you need to file.
https://www.irs.gov/help/ita/do-i-need-to-file-a-tax-return
