Last year—which was strange in so many ways—Tax Day was delayed from April 15 until July 15. This year isn’t exactly normal, but this year the IRS repeatedly said there would be no delay.

But then, the IRS announced that Tax Day for individuals is extended to May 17. If you need more time than that, you can request a filing extension until Oct. 15 by filing Form 4868 through your tax professional, tax software or using the Free File link on IRS.gov. Filing Form 4868 gives taxpayers until Oct. 15 to file their 2020 tax return but does not grant an extension of time to pay taxes due.

That means you should pay their federal income tax due by May 17, 2021, to avoid interest and penalties. But does this extension apply to everything? Not hardly. Most notably, this relief does not apply to estimated tax payments that are due on April 15, 2021. These payments are still due on April 15. Estimated tax payments are often misunderstood.

Taxes must be paid as taxpayers earn or receive income during the year, either through withholding or estimated tax payments. In general, estimated tax payments are made quarterly to the IRS by people whose income isn't subject to income tax withholding, including self-employment income, interest, dividends, alimony or rental income. Most taxpayers automatically have their taxes withheld from their paychecks and submitted to the IRS by their employer. But if you aren’t an employee or you have significant other income, watch out.

On the positive side, the IRS announced that individuals have until May 17, 2021, to meet certain other deadlines that would normally fall on April 15, such as making IRA contributions and filing certain claims for refund. IRS Notice 2021-21 PDF provides details on additional tax deadlines which have been postponed until May 17. This follows the previous announcement from the IRS about the usual filing deadline.

IRAs and health savings accounts. The IRS is automatically postponing to the same date the time for individuals to make 2020 contributions to their individual retirement arrangements (IRAs and Roth IRAs), health savings accounts (HSAs), Archer Medical Savings Accounts (Archer MSAs), and Coverdell education savings accounts (Coverdell ESAs). This postponement also automatically postpones to May 17, 2021, the time for reporting and payment of the 10% additional tax on amounts includible in gross income from 2020 distributions from IRAs or workplace-based retirement plans. Notice 2021-21 also postpones the due date for Form 5498 series returns related to these accounts to June 30, 2021.

2017 unclaimed refunds. For tax year 2017 Federal income tax returns, the normal April 15 deadline to claim a refund has also been extended to May 17, 2021. The law provides a three-year window of opportunity to claim a refund. If taxpayers do not file a return within three years, the money becomes property of the U.S. Treasury. The law requires taxpayers to properly address, mail and ensure the tax return is postmarked by the May 17, 2021, date.

Of course, many people won’t be ready to file their taxes by May 17. You can now make the decision later whether to file on time (by May 17) or to extend until October 15. Apart from the pandemic, there are some new law changes and many other reasons that have caused this tax filing season—like last year—to be difficult. And tax returns, it bears stressing, are important. Even if you do not prepare your own, you should read and understand the return to the best of your ability. After all, you must also sign it under penalties of perjury. You should review it before signing, and alert the return preparer to any mistakes you discover.

Robert W. Wood is a tax lawyer and managing partner at Wood LLP. He can be reached at Wood@WoodLLP.com