With the exemption of 2020, filing of income tax returns is due on April 15th annually.
Income tax return summarizes all income earned from the previous year that includes, but not limited to: wages, dividends, commissions, etc. Allowed expense deductions (itemized or standard) are subtracted from it. The leftover is your taxable income.
Your tax rate bracket is determined based on your taxable income and that $1 difference makes a difference in how much tax you owe the IRS. Later, I will give a hypothetical example to show how tax planning can prevent owing a lot.
For now, all you need to know is that the deadline is extended to July 15, 2020–a generous 3 months or 1 whole quarter to get it done.