08/27/2026
Tax deadlines do not stop after April.
The Taxpayer Advocate Service has published a helpful 2026 tax calendar covering important dates for individuals and businesses, including the September 15 estimated-tax deadline and the October 15 deadline for individual returns filed on extension.
A useful reference to bookmark and review throughout the year:
https://www.taxpayeradvocate.irs.gov/news/tax-tips/your-tax-to-do-list-important-tax-dates/2026/03/
The Taxpayer Advocate Service shares information on important tax deadlines for individuals and businesses.