Form 8878 vs 8879: Which One Do You Need?
Form 8879 authorizes e-filing a tax return; Form 8878 authorizes e-filing an extension with a payment. Here is the difference, and when you need each one.
By Rashad Bayram | Published: 7/14/2026
The short answer: Both forms are IRS e-file signature authorizations that let an ERO enter the taxpayer's PIN, but they cover different filings. Form 8879 authorizes e-filing the tax return itself (Form 1040). Form 8878 authorizes e-filing an extension (Form 4868 or 2350), and only when the taxpayer is paying a balance due by electronic funds withdrawal at the same time. Neither is sent to the IRS; the preparer keeps them for three years. If you e-file returns for clients, you have signed a stack of 8879s. The 8878 shows up far less often, which is exactly why the difference gets fuzzy. Here it is, cleanly. What Form 8879 is Form 8879 , the IRS e-file Signature Authorization, is how a taxpayer authorizes their preparer to put a Personal Identification Number on their electronically filed income tax return. It is the electronic stand-in for signing the return. The taxpayer reviews the return, signs the 8879, and the ERO can then transmit the 1040 without a wet signature on paper. This is the form in play on almost every e-filed individual return. What Form 8878 is Form 8878 is the IRS e-file Signature Authorization for an Application for Extension of Time to File , that is, for Form 4868 (the automatic extension) or Form 2350. It authorizes the ERO to enter the taxpayer's PIN on that extension request. The catch that trips people up: you only need the 8878 when the extension comes with a payment made by electronic funds withdrawal . An extension is a request for more time, not more money, so if the taxpayer files it with no payment, or pays their estimated balance some other way, there is generally no 8878 to sign. The difference in one line Form 8879 Form 8878 Authorizes e-filing of The tax return (Form 1040) An extension (Form 4868 / 2350) When you need it Almost every e-filed return Only an extension paid by electronic funds withdrawal Filed with the IRS? No, the ERO keeps it No, the ERO keeps it Retention 3 years 3 years So the plain rule: 8879 is for the return, 8878 is for a paid extension. If there is no return being transmitted, and no electronic payment on an extension, you are not looking at either one. When you actually reach for the 8878 In practice the 8878 is a narrow tool. You need it when all three are true: you are filing an extension, you are doing it electronically, and the taxpayer is authorizing an electronic funds withdrawal to pay a balance with it. Miss any one of those and the 8878 drops out. That is why a preparer can go a whole season handling dozens of 8879s and only a handful of 8878s. What the two forms share Underneath the different filings, they behave the same way: They authorize a PIN. Both let the ERO enter or generate the taxpayer's Self-Select or Practitioner PIN so the filing can go through electronically. They stay with you. Neither is transmitted to the IRS. The ERO holds the signed form as the authorization record. They must be kept for three years. Per IRS Publication 1345 , retain the signed form for three years from the return due date or the IRS received date, whichever is later. They can be signed electronically , provided the ERO meets the IRS signing and identity-verification requirements for how the signature is collected. Those requirements, and the responsibility to meet them, sit with the preparer, not the software. Collecting them without the paper chase Whichever form applies, the annoying part is the same: getting it signed and keeping a clean, retrievable record for three years. That is one of the steps I built Taxformify to handle. You upload the 8879 or 8878, send it to the client to sign through a secure portal, and reminders go out on day three and day five if it is still outstanding. When they sign, you get the signed copy back with a Certificate of Signature that records the signing date, a timestamp, and a verifiable link, the kind of dated, retained record the three-year rule asks for. One boundary is worth stating outright, because it decides whether the flow above is the right tool at all. Taxformify does not run knowledge-based authentication. The IRS requires KBA whenever a taxpayer electronically signs an 8879 or 8878 remotely , so that specific case needs a signing provider with KBA built in. Use Taxformify for in-person signing, for the print-and-pen-sign-then-upload route that Publication 1345 excludes from the remote electronic signature definition, and for the Canadian T183 , which has no KBA requirement at all. When Form 8879 requires KBA sets out exactly where each line falls. Two other things stay yours, by design: verifying the client's identity to the IRS's standard for the way you are collecting the signature, and transmitting the return or extension itself. Taxformify captures and retains the signature cleanly and chases it for you; it does not file for you. To see it run on a real form, book a short demo . The forms are simple once the distinction is clear. The work is collecting the signature and keeping the record, and that is the part worth automating. Where signatures sit in the wider filing-season workflow is covered in tax workflow automation . One note: this is general information, not tax advice, and IRS procedures change. Confirm the current rules for the form and year you are filing against the IRS sources below. Frequently Asked Questions What is the difference between Form 8878 and Form 8879? Both authorize an electronic return originator (ERO) to enter or generate the taxpayer's PIN, but for different filings. Form 8879 is the signature authorization for the tax return itself (Form 1040). Form 8878 is the signature authorization for an application for an extension of time to file (Form 4868 or Form 2350), and it is only needed when the taxpayer is authorizing an electronic funds withdrawal with that extension. What is Form 8879 used for? Form 8879 is the IRS e-file Signature Authorization. It lets the taxpayer authorize the ERO to enter their Personal Identification Number on their electronically filed income tax return, so the return can be transmitted without a wet signature. The ERO keeps the signed 8879; it is not sent to the IRS. When do you need Form 8878? You need Form 8878 only when you are e-filing an extension (Form 4868 or Form 2350) and the taxpayer is paying a balance due by electronic funds withdrawal at the same time. If the extension carries no payment, or the taxpayer pays another way, Form 8878 is generally not required. Most straightforward extensions do not need it. Do you file Form 8879 or 8878 with the IRS? No. Neither form is filed with the IRS. The ERO collects the taxpayer's signature and keeps the form on file as the authorization record. It only has to be produced if the IRS requests it. How long do you keep Form 8879 and 8878? The ERO must retain the signed 8879 or 8878 for three years from the return due date or the date the IRS received the return, whichever is later, per IRS Publication 1345. An electronic copy with a clear signing date and audit trail satisfies the requirement and is easier to produce on request than a paper file. Disclaimer This article is for general informational purposes and is not tax advice. Tax laws change frequently and individual situations vary. TaxFormify does not provide tax advice. Consult a licensed CPA or enrolled agent for guidance on your specific circumstances. Further reading KBA and Form 8879: When the IRS Requires an Identity Quiz : the identity-verification rule that applies when either form is e-signed remotely. T183 Electronic Signature: the CRA Rules : the Canadian counterpart to the 8879. Tax Workflow Automation: A Day in the Life : where signatures fit in the season. Stop Chasing Clients for Tax Documents : removing the chase from the whole workflow. Sources IRS, About Form 8879 (IRS e-file Signature Authorization) IRS, About Form 8878 (IRS e-file Signature Authorization for Form 4868 or Form 2350) IRS, About Form 4868 (Application for Automatic Extension of Time) IRS, Publication 1345 (Handbook for Authorized IRS e-file Providers)