Form 5558 is the IRS application for a one-time extension to file Form 5500, 5500-SF, 5500-EZ and Form 8955-SSA. Filed complete on or before the normal due date, it's approved automatically to the 15th day of the 3rd month after that date. For a calendar-year plan due on the last day of July, that's 15 October. Since 1 January 2025 you can file it electronically through EFAST2 as well as on paper.
Everything here comes from Form 5558 and its instructions (Rev. January 2025) and the 2025 Instructions for Form 5500-EZ, as of October 2026.
What Form 5558 extends, and what it doesn't
| Return | Covered by Form 5558? |
|---|---|
| Form 5500 | Yes |
| Form 5500-SF | Yes |
| Form 5500-EZ | Yes |
| Form 8955-SSA | Yes, on the same Form 5558 as the plan's 5500 if you like |
| PBGC Form 1, the annual premium payment | No, an extension doesn't move this |
It's one form per plan. An employer with a defined benefit plan and a profit-sharing plan files two. Lists of other plans attached to the form aren't processed, though a DCG reporting arrangement can use a single Form 5558 for its Form 5500.
The deadline and how much time you get
Form 5500-EZ is due by the last day of the 7th calendar month after the plan year ends. File Form 5558 on or before that normal due date and the extension runs to no later than the 15th day of the 3rd month after it. A weekend or holiday due date rolls to the next business day.
| Plan year ends | Normal due date | Extended due date |
|---|---|---|
| 31 December | 31 July | 15 October |
| 30 June | 31 January | 15 April |
| 31 March | 31 October | 15 January |
The IRS doesn't send approved copies back. A timely, complete Form 5558 is the approval.
When you don't need Form 5558 at all
This is the shortcut most small employers miss. Form 5500, 5500-SF, 5500-EZ and 8955-SSA filers get an automatic extension to the extended due date of the employer's federal income tax return, without Form 5558, when both conditions are met:
- the plan year and the employer's tax year are the same; and
- the employer has an extension for its income tax return to a date later than the plan return's normal due date.
The limit is that this automatic extension can't then be stretched further by filing Form 5558 after the plan return's normal due date has passed.
Filling in the form
- Part I, A: the name and address of the employer or plan administrator, matching the annual return. A new address here won't update IRS records; use Form 8822-B for that.
- Part I, B: the employer's nine-digit EIN. Don't use a social security number in its place.
- Part I, C and D: the plan's formal name and three-digit plan number, starting at 001 and never reused.
- Part I, E: the plan year end date.
- Line 1: tick only if this is the plan's first Form 5500 series return.
- Line 2: the extended date for Form 5500, 5500-SF or 5500-EZ.
- Line 3: the extended date for Form 8955-SSA.
Don't attach the Form 5500 or 8955-SSA to it, and use the January 2025 revision: the IRS says older versions cause delays.
Where to send it
Electronically through EFAST2, or on paper to the Department of the Treasury, Internal Revenue Service Center, Ogden, UT 84201-0045. Private delivery services can't deliver to a PO box, so check the IRS street address list if you're couriering it.
What missing the deadline costs
The 5500-EZ instructions put the section 6652(e) penalty at $250 a day, up to $150,000 per plan year, for one-participant and foreign plans that file late, as of October 2026. A timely Form 5558 costs nothing to file. For one-participant plans that have already missed it, the IRS Late Filer Penalty Relief Program under Rev. Proc. 2015-32 is the route back, filed on paper.
Getting the EIN and plan number right
Most rejected or delayed extensions trace back to identifiers that don't match the annual return. The employer or plan administrator named on Form 5558 should be the same one named on the Form 5500 series return. An entity without an EIN has to apply for one straight away, online at IRS.gov/EIN where it's issued once the details validate, or on Form SS-4 by fax or post. A business organized outside the United States can apply by phone on 267-941-1099.
The plan number trips people up too. Plans are numbered in order from 001, and once a number is used for a plan, it stays with that plan for every future filing and can't be given to another plan, even after the first one is terminated.
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If you're late for a one-participant plan
Under the Late Filer Penalty Relief Program, a one-participant or foreign plan files a complete paper Form 5500-EZ for each missed year, never through EFAST2, with this printed in red above the title on page one: Delinquent Return Submitted under Rev. Proc. 2015-32, Eligible for Penalty Relief.
The verdict
If your plan year matches your business tax year and you've extended your business return, you may not need Form 5558 at all. Otherwise file it before the end of July for a calendar-year plan, one per plan, and put the 8955-SSA on the same form. It's a two-minute job that buys two and a half months.
Frequently asked questions
What is Form 5558?
It's the IRS application for a one-time extension of time to file the Form 5500 series and Form 8955-SSA.
How long is the Form 5558 extension?
Up to the 15th day of the 3rd month after the return's normal due date, so 15 October for a calendar-year plan.
When is Form 5558 due?
On or before the normal due date of the return you're extending, which for Form 5500-EZ is the last day of the 7th month after the plan year ends.
Can Form 5558 be filed electronically?
Yes. Since 1 January 2025 it can be filed through EFAST2 or on paper with the IRS in Ogden.
Does Form 5558 extend the PBGC premium?
No. An extension to file the Form 5500 series doesn't extend PBGC Form 1, Annual Premium Payment.
Do I need a separate Form 5558 for each plan?
Yes. A separate Form 5558 is needed for each plan, though one form can extend both a plan's Form 5500 series return and its Form 8955-SSA.
Will the IRS confirm my Form 5558 extension?
No. Approved copies aren't returned; a timely, complete Form 5558 is automatically approved.
