What is the standard federal tax filing deadline for individual returns, and what happens if you file for an extension?

Individual federal tax returns are due on April 15th each year (adjusted to the next business day when it falls on a weekend or holiday). Filing Form 4868 grants an automatic six-month extension to October 15th to submit your return, with no questions asked and no approval required. Critically, an extension to file is not an extension to pay — any taxes owed are still due by April 15th, and interest plus a failure-to-pay penalty of 0.5% per month accrues on unpaid balances after the original deadline. Estimating and paying your tax liability by April 15th while filing the extension form avoids penalties on the payment.