Missing a W-2, 1099, or K-1? What to Do Before Your Extended Deadline

It is possible for a missing tax form to make it look as if the return cannot be completed, but this situation is usually not true since W-2s and the majority of 1099s have a backup figure that you can construct from your own records. The K-1 is the exception. You should first ask your employer, the payer, or the partnership for the 2025 form and then decide if you can report that income accurately based on your own records.

The deadline will depend on whether you have asked for an extension. For the majority of taxpayers, the time in which an extension could have been obtained for the year 2025 closed on April 15, 2026. Those residing in an area declared by the IRS to be affected by a disaster might have been given more time. If you did apply for an extension, your federal tax return is then due on October 15, 2026; if you did not apply, you should file as soon as possible using the best records that you have.

An extension is a filing extension, not a way of delaying the payment of your tax bill; any tax that you owed for 2025 was still due on April 15, 2026, and the IRS imposes interest on the amount that is still unpaid until the full amount has been paid, so you should pay as much as you can while you are waiting for the document. Our article on paying an estimated tax balance includes information about payment arrangements and penalties.

If you file Form 1040, these federal dates are yours. Businesses extend on Form 7004 and have their own dates.

A Late K-1 Is the Hardest Missing Document to Work Around

All the documents listed below were supposed to have been sent to you months ago. If one has not appeared by late September, then the issuer is late, and the action you can take will depend on the type of form.

For most of these you can draw up a fallback using the records that you already have. The K-1 is the exception, since it shows your share of an entity’s income, deductions, and credits, and only the entity has those figures.

W-2 Not Received: Call the IRS and Use Form 4852

It would be a mistake to think that a missing W-2 leaves you unable to proceed. The IRS provides four steps:

1. Check with your employer. Make sure that the form was sent, and check the address it was sent to.
2. After February has passed, telephone the IRS. If your W-2 hasn’t arrived yet, you can call 800-829-1040. Make sure you have ready your name, address including the ZIP code, date of birth and Social Security number, as well as your employer’s name, address with ZIP code, and their EIN if you have it. The IRS will then contact your employer and send you Form 4852, which is a substitute for Form W-2.
3. Complete Form 4852 if your W-2 hasn’t arrived by the time you need it. Estimate your wages and the amount of tax withheld from your most recent pay stub, then fill in Form 4852 with that information and include it with your tax return.
4. Amend if the actual W-2 differs. If your W-2 comes in after you file and the figures on it differ from your estimates, then you must file Form 1040-X.

Form 4852 can also be used when a Form 1099-R is missing or incorrect. With that option available, a missing W-2 on its own is very seldom a valid reason for holding your return past October 15. Our guide to filing without a W-2 gives a more detailed account of the Form 4852 process.

You ought to also check your IRS Individual Online Account, as it displays the wage and income information which employers and payers have reported, and wage and income transcripts can be obtained free of charge. The IRS says that data for the current year is usually available by the first week of February, although if your employer never filed the form it will not show up. The fact that the account is empty is no justification for omitting the income; in the case of a W-2, it means that you should use Form 4852.

1099 Not Received: Your Records Are the Fallback

Other than the 1099-R, there is no substitute form in the 1099 series, which means you’ll have to report the income yourself on the basis of what you can prove. Start by determining who was responsible for sending the form and what income it refers to. First, contact that payer or the issuing agency, since the IRS recommends that you do, and ask for the form or the figures from it. Then, compare the amount with:

• Bank statements
• Brokerage and investment statements
• Invoices and client payment records
• Closing documents for a property sale

The wage and income transcript will show what the payer reported, provided that they reported it. In most cases you will be able to reconstruct a 1099 for work that you invoiced. A 1099-B for which you do not know the cost basis is a different matter, and it is precisely this uncertainty that tips the decision toward waiting for the form.

K-1 Delayed: The Partnership’s Deadline Sets Yours

A K-1 has to be sent to you by the due date of the partnership’s return, including any extension. In the case of 2025, that date was March 16, 2026, or September 15, 2026 if the partnership had applied for an extension on Form 7004. This could put you in a difficult situation since, if the partnership did extend, your K-1 might legally be sent as late as September 15, 2026, which is a month before your own October 15 deadline.

If the K-1 is past due, you should get in touch with the partnership or its tax preparer, find out when it will be sent out, and ask if they can give you the figures at this time. The fact that S corporations and trusts use their own filing dates means that you should ask them directly about the timing.

If October 15 is approaching and you have not yet received your K-1, it is advisable to seek advice from a tax professional regarding how to report the best figures that the partnership can provide. You can make an amendment using Form 1040-X once the K-1 has arrived. Filing by October 15 will ensure that your return is submitted on time. However, if you wait past October 15 for the K-1, a return that would have been on time will be considered late and the failure-to-file penalty (which is usually 5% of any unpaid tax for each month or part of a month) will then apply.

File on an Estimate Only If You Can Defend the Numbers

You can use approximate figures to file your tax return if the form hasn’t been sent to you, but the effectiveness of that approach depends on how reliable your approximate figures are.

Filing now makes sense when:

• There are trustworthy records of the income.
• The amount of tax withheld can be found on a pay stub or statement.
• The missing form is not likely to show different figures.
• You asked the issuer for the form and it has still not arrived.

Waiting for the form makes sense when:

• You do not know the correct amount of income or withholding.
• The missing form might affect deductions or credits that appear elsewhere on your return.
• You are waiting for a K-1 or another form that you cannot reconstruct from your own records.

When you file an approximate return, you will be required to fill in a second return on Form 1040-X once the actual form shows different amounts. This means that you will have to go through additional paperwork and carry out another check of your records, so in the situation where you file early but then have to make amendments later, you won’t have saved any time or effort. Moreover, you will still be responsible for accurately reporting your income even if the other party is the one who is late.

Your Filing Options Now for Tax Year 2025

If you extended by April 15, 2026. Filing Form 4868 gives you an automatic extension; therefore, it was enough to make a timely request, and an online payment designated as an extension payment also acted as such a request. The deadline for your federal tax return is October 15, 2026. Use the time still available to look for the missing form, and if it does not arrive, file the return by that date with the information you have.

If you did not extend. Your return is now late. You should file it as soon as possible, using Form 4852 or your own records where a document is missing. See what to do if you missed the deadline.

If you file on paper. Your return is considered to have been filed on time if it is postmarked and deposited in the mail by the due date. Make sure you keep proof of mailing.

Missing Tax Document Checklist Before October 15, 2026

• Identify each missing form and who was responsible for issuing it.
• Get in touch with the employer, the payer, or the partnership and request it.
• If you are missing a W-2 or a 1099-R, call the IRS at 800-829-1040 and request Form 4852.
• Look at the wage and income data reported in your IRS Individual Online Account.
• Collect the pay stubs, bank statements, and invoices that show your income.
• Work out whether you can report each item accurately or need the actual form.
• Pay any remaining 2025 balance to limit further interest.
• File by October 15, 2026, or as soon as possible if you did not extend.
• If a form arrives later with different figures, file Form 1040-X.

Related Tax Extension Situations

There are other reasons why people may need extra time. See our other tax extension special cases for disaster relief, military service, and filing from abroad. For information on deadlines and what to do next, visit Tax Extension Help.

Ready to file?

When your documents are in hand, or your estimates are good enough to stand by, finish your federal tax return with FileTax.com before October 15, 2026.