--- title: "Form 5500 identity: EIN, plan number, and ACK ID" description: "Distinguish a retirement plan from its individual Form 5500 submissions. Compare sponsor EIN, plan number, ACK_ID, reporting periods, and amendments." canonical: "https://scalewithsearch.com/articles/form-5500-plan-identity-ein-plan-number-ack-id" --- ## Site navigation - [Scale With Search](https://scalewithsearch.com/) - Services - Services - [AI systems](https://scalewithsearch.com/ai-systems) - [Site build](https://scalewithsearch.com/work#site-build) - [Whole website fix](https://scalewithsearch.com/work#whole-website-fix) - [Content library with SEO](https://scalewithsearch.com/work#content-library) - [Working session](https://scalewithsearch.com/audit) - Start here - [Send your brief](https://scalewithsearch.com/work#send-your-brief) - [Example scope](https://scalewithsearch.com/work#review-the-example-scope) - [Prices and terms](https://scalewithsearch.com/work#prices-and-terms) - Industries - Real estate - [Real estate agents and teams](https://scalewithsearch.com/for/real-estate) - [Platforms, ownership, and IDX](https://scalewithsearch.com/for/real-estate/real-estate-website-platforms-ownership-idx) - [Search, content, and AI](https://scalewithsearch.com/for/real-estate/real-estate-search-content-ai) - [Inquiries, campaigns, and handoffs](https://scalewithsearch.com/for/real-estate/real-estate-website-inquiries-campaigns-handoffs) - [Buyer, seller, and local pages](https://scalewithsearch.com/for/real-estate/real-estate-buyer-seller-local-resources) - [Rules, privacy, and trust](https://scalewithsearch.com/for/real-estate/real-estate-website-rules-privacy-trust) - Browse by business - [Trades and home services](https://scalewithsearch.com/for/#group-trades) - [Health, wellness, and animal care](https://scalewithsearch.com/for/#group-practices) - [Law, finance, and IT](https://scalewithsearch.com/for/#group-professional) - [Marketing and SEO agencies](https://scalewithsearch.com/for/#group-agencies) - [Shops and manufacturers](https://scalewithsearch.com/for/#group-manufacturing) - [Restaurants, shops, studios, and nonprofits](https://scalewithsearch.com/for/#group-local-services) - Chiropractic practices - [Chiropractic and wellness practices](https://scalewithsearch.com/for/chiropractic-and-wellness-practices) - [Chiropractic and physical therapy clinics](https://scalewithsearch.com/for/chiropractic-and-physical-therapy-clinics) - [All industries](https://scalewithsearch.com/for/) - Resources - Free tools - [AI readiness check](https://scalewithsearch.com/check) - [Free tools](https://scalewithsearch.com/tools/) - [Free Starter Kit](https://scalewithsearch.com/kit/business-memory-starter-kit.zip) - Guides - [AI-native library](https://scalewithsearch.com/ai-native) - [Industry intelligence](https://scalewithsearch.com/intelligence) - [Office job guides](https://scalewithsearch.com/guides/) - [Business memory](https://scalewithsearch.com/articles/business-memory-for-ai-agents-guide) - [Agent governance](https://scalewithsearch.com/articles/ai-agent-governance-guide-small-business) - [Migration and ownership](https://scalewithsearch.com/articles/leaving-vendor-ai-memory-guide) - Articles - [All articles](https://scalewithsearch.com/articles/) - [What changed](https://scalewithsearch.com/changes/) - About - Evidence - [Proof](https://scalewithsearch.com/proof) - Scale With Search - [About](https://scalewithsearch.com/about) - [How it works](https://scalewithsearch.com/how-it-works) # Form 5500 plan identity: separate sponsor EIN, plan number, and filing acknowledgment Before comparing two retirement-plan filings, establish what each identifier identifies. A sponsor, a plan, a reporting period, and a submission require separate places in your research notes. Combining them into one employer row can turn an amendment into apparent plan growth. The 2025 Form 5500 instructions identify a plan through its sponsor employer identification number, or EIN, together with its three-digit plan number. DOL's datasets guide identifies an individual filing through its acknowledgment identifier, `ACK_ID`. Those identifiers answer different research questions. [2025 instructions, line 1b, page 17](https://www.dol.gov/sites/dolgov/files/ebsa/employers-and-advisers/plan-administration-and-compliance/reporting-and-filing/form-5500/2025-instructions.pdf#page=17); [datasets guide, page 2](https://www.dol.gov/sites/dolgov/files/ebsa/pdf_files/form-5500-datasets-guide.pdf#page=2). For an employer-plan advisory practice, start with a plan history and preserve the submissions beneath it. The [retirement-plan intelligence overview](/intelligence/financial-advisors) describes the wider research workflow. This guide handles the narrower identity decision before any count or provider comparison. ## Give each identifier one job The following reference applies to the 2025 core Form 5500 dataset. Keep the source form and year beside the field name. A familiar label from another file is insufficient evidence that its meaning matches. Table: Identity fields in the 2025 core Form 5500 dataset | Research item | Core field | What to inspect | | --- | --- | --- | | Sponsor identifier | `SPONS_DFE_EIN` | Nine-character text field corresponding to sponsor EIN on line 2b | | Plan number | `SPONS_DFE_PN` | Three-character text field corresponding to line 1b | | Filing identifier | `ACK_ID` | Identifier for the particular filing submission | | Reporting-period start | `FORM_PLAN_YEAR_BEGIN_DATE` | Beginning date in Part I | | Reporting-period end | `FORM_TAX_PRD` | Ending date in Part I | | Amendment marker | `AMENDED_IND` | Amended-return checkbox in Part I, line B | | Receipt context | `DATE_RECEIVED`, `FILING_STATUS` | System-generated receipt date and status | The [2025 core layout](https://www.askebsa.dol.gov/FOIA%20Files/2025/Latest/F_5500_2025_Latest_layout.txt) supplies field types and sizes. The [2025 data dictionary](https://www.dol.gov/sites/dolgov/files/ebsa/about-ebsa/our-activities/public-disclosure/foia/form-5500-2025-data-dictionary.zip) maps fields onto the form. The [datasets guide, pages 1 and 2](https://www.dol.gov/sites/dolgov/files/ebsa/pdf_files/form-5500-datasets-guide.pdf) explains system fields and submission identity. All were checked on October 28, 2026. Preserve identifiers as text. Plan number `001` must remain `001` in a worksheet, an attachment label, and a comparison note. The layout designates both EIN and plan number as text. Treating a plan number as an ordinary quantity discards meaningful presentation and makes manual reconciliation harder. The sponsor EIN also differs from an administrator EIN. The instructions assign those entries to lines 2b and 3b respectively. A provider's identifier should not replace either one because its name appears elsewhere in the filing. [2025 instructions, pages 17 and 18](https://www.dol.gov/sites/dolgov/files/ebsa/employers-and-advisers/plan-administration-and-compliance/reporting-and-filing/form-5500/2025-instructions.pdf#page=17). ## Use EIN and plan number together Line 1b describes the plan number and sponsor EIN together as the plan identifier used by the agencies. It also instructs filers to keep using a plan number for that plan. A terminated plan's number must not become another plan's number. [2025 instructions, line 1b, page 17](https://www.dol.gov/sites/dolgov/files/ebsa/employers-and-advisers/plan-administration-and-compliance/reporting-and-filing/form-5500/2025-instructions.pdf#page=17). For research, record the pair before deciding that rows describe the same plan. Two plans can share one sponsor EIN while retaining different plan numbers. Two unrelated sponsors can use the same three-digit plan number. Neither half of the pair should carry the matching decision alone. Use the reported names as supporting evidence. Preserve their original spelling alongside any readable display name. If a later filing changes a name, keep the earlier name in history. Replacing every historical label with today's label removes evidence a reviewer may need. The 2025 instructions address reported identity changes on line 4. That line asks for prior sponsor identity, plan name, and plan number when specified names or EIN change. The core layout includes `LAST_RPT_SPONS_EIN`, `LAST_RPT_SPONS_NAME`, `LAST_RPT_PLAN_NAME`, and `LAST_RPT_PLAN_NUM`. [Instructions, line 4, page 18](https://www.dol.gov/sites/dolgov/files/ebsa/employers-and-advisers/plan-administration-and-compliance/reporting-and-filing/form-5500/2025-instructions.pdf#page=18); [2025 core layout](https://www.askebsa.dol.gov/FOIA%20Files/2025/Latest/F_5500_2025_Latest_layout.txt). Treat those prior values as evidence requiring examination. Do not assume every changed EIN means a new plan. Do not assume every similar name proves continuity. When the link remains uncertain, preserve both reported identities and hold the comparison. ## Use ACK_ID for a submission DOL explains that a Form 5500 or Form 5500-SF submission and its associated schedules share an acknowledgment identifier. That identifier connects records belonging to one submission. It does not serve as a permanent identifier for the plan across annual filings. [Datasets guide, page 2](https://www.dol.gov/sites/dolgov/files/ebsa/pdf_files/form-5500-datasets-guide.pdf#page=2). A reviewer opening a schedule should therefore retain the submission reference. Matching a schedule through sponsor name alone could attach evidence from another year or version. A provider observation needs the filing it came from, even when the sponsor name looks unchanged. Keep the original acknowledgment identifier in the evidence note. Avoid shortening it to a final few characters in the underlying record. A shortened display label can help a meeting, but the full source identifier should remain available for verification. That discipline matters when a filing changes. You need to know which submission supplied a count, a provider observation, or a note. Otherwise, a comparison may quietly combine the original core record with evidence from an amendment. ## Work through one fictional sponsor This example is synthetic. The sponsor name, EIN, dates, and acknowledgment labels do not represent a real filing. The acknowledgment labels are mnemonic placeholders, not authentic EFAST2 identifiers. Assume Example Harbor Works sponsors two pension plans. Its fictional EIN is `012345678`. Plan `001` and plan `002` remain separate throughout the worksheet. Table: Fictional plan identities and filing versions | Sponsor EIN | Plan number | Reporting period | Submission label | Review note | | --- | --- | --- | --- | --- | | `012345678` | `001` | 01/01/2025 to 12/31/2025 | `EXAMPLE-001-ORIGINAL` | Original submission retained | | `012345678` | `001` | 01/01/2025 to 12/31/2025 | `EXAMPLE-001-AMENDED` | Amendment for the same reporting period | | `012345678` | `002` | 01/01/2025 to 12/31/2025 | `EXAMPLE-002-ORIGINAL` | Different plan under the same sponsor | The three rows represent two plan identities and three submissions. They do not represent three employers or three annual observations of growth. For plan `001`, the reviewer must resolve the original and amended versions before selecting comparison values. Suppose the amendment changes a participant figure from 140 to 146. Preserve both values with their submission labels. Record why the reviewer selected one version for the comparison. The six-person difference describes a filing revision in this example. It does not describe six newly hired employees. Now suppose next year's record uses another sponsor EIN but reports the old identity on line 4. Add an unresolved continuity question. Ask the plan specialist to inspect both filings and their supporting records. Do not merge them because a spreadsheet lookup finds the old name. ## Resolve amendments before building a time series The 2025 instructions require an amended filing to replace the complete previous submission, including required schedules and attachments. They do not describe an amendment as a standalone patch containing only changed fields. [2025 instructions, Amended Return/Report, page 6](https://www.dol.gov/sites/dolgov/files/ebsa/employers-and-advisers/plan-administration-and-compliance/reporting-and-filing/form-5500/2025-instructions.pdf#page=6). DOL publishes both “All” and “Latest” datasets. “All” can include amended or duplicate submissions for a single plan and form year. “Latest” includes the latest filing received for a plan with `FILING_RECEIVED` status. [Datasets guide, page 1](https://www.dol.gov/sites/dolgov/files/ebsa/pdf_files/form-5500-datasets-guide.pdf#page=1). Write which dataset you used beside the download date. Use the original submissions when examining revision history. Use the documented selection rule when preparing a single-period comparison. The word “Latest” alone does not describe your entire historical selection method. Retain the amendment marker, receipt date, and filing status. A later receipt date helps establish submission chronology. It does not explain why the filing changed. If the amendment reason is unavailable, leave that reason unresolved. ## Separate form year from reporting period DOL's catalog explains that datasets from 2009 onward represent the form year printed on the form. A dataset's year is therefore a different concept from the period reported in Part I. [DOL datasets catalog](https://www.dol.gov/index.php/agencies/ebsa/about-ebsa/our-activities/public-disclosure/foia/form-5500-datasets). Record the actual beginning and ending dates from each filing. A filename containing `2025` cannot replace those dates. A receipt date in a later calendar year also cannot replace the reporting-period end date. The filing tips discuss calendar, fiscal, and short plan years. Their period examples reinforce the need to read Part I rather than infer coverage from a download label. [DOL filing tips, reporting-period section](https://www.dol.gov/agencies/ebsa/employers-and-advisers/plan-administration-and-compliance/reporting-and-filing/forms/efast2-form-5500-filing-tips). When two records cover different periods, describe the difference before comparing their figures. A short reporting period needs its own note. Preserve the source dates without inventing an annualized result. ## Keep weak matches out of accepted history A sponsor name, provider name, or ZIP can help locate a candidate record. None supplies the plan identifier described in line 1b. Use them to find evidence, then establish the plan and submission through the controlling fields. For example, one fictional sponsor name appears on both plans above. Name matching alone would collapse them. A shared provider label would add no missing plan number. A shared ZIP would add no missing submission reference. Keep candidate matches separate from accepted matches. Give each unresolved case a precise question, such as “Does line 4 connect this changed EIN to the earlier plan?” Assign a reviewer and record the evidence needed to answer it. ## Use a manual comparison worksheet Create one worksheet entry for each proposed link between filings. The following fields are a recommended research practice, not another government form. Table: Manual plan-continuity review worksheet | Worksheet field | What the reviewer records | | --- | --- | | Source A and source B | Full filing references, URLs, form years, and retrieval dates | | Reported identity | Sponsor EIN and three-character plan number from each source | | Period | Exact beginning and ending dates from both filings | | Version | ACK_ID, amendment marker, received date, status, and dataset selection | | Changed identity evidence | Prior values on line 4 and the supporting filing pages | | Unresolved question | Missing identifier, conflicting period, or unexplained identity change | | Decision | Accepted link, separate plans, or held comparison, with reason | | Review record | Responsible reviewer, review date, and evidence inspected | Before accepting the worksheet, reopen the referenced filing. Check that every copied identifier retains its leading zeros. Confirm that the comparison uses one chosen submission for each period. Leave uncertainty visible when the available records cannot settle it. Once identity is resolved, use the [participant-count field guide](/articles/form-5500-participant-counts-active-total-account-balances) to choose a comparable size measure. Preserve these decisions in the firm's [owned business record](/articles/business-memory-for-ai-agents-guide). Future researchers should see both the accepted history and its evidence. The [financial-advisor overview](/for/financial-advisors) covers record boundaries inside the practice. Scale With Search can scope a research function around your sources, comparison rules, and responsible reviewers through the [written work brief](/work). Plan interpretation and professional decisions remain with your qualified team. Continue the website review: [AI-native financial advisors: the first functions to build](/articles/ai-native-financial-advisors-first-functions); [Financial advisor AI rules: data, approvals, and spend](/articles/financial-advisor-ai-rules-data-approvals-spend); [Financial advisor award badges: verify the website claim](/articles/financial-advisor-awards-ratings-website); [Financial advisor bios: link to registration records](/articles/financial-advisor-bio-registration-links); [Financial advisor meeting requests: limit the first form](/articles/financial-advisor-first-meeting-request-form); [Form CRS on a financial advisor website: check the link](/articles/financial-advisor-form-crs-website-link); [Financial advisor Google profiles: practitioner or firm?](/articles/financial-advisor-google-practitioner-profile); [Financial advisor newsletter archives: publish approved text](/articles/financial-advisor-newsletter-website-archive); [Financial advisor niche pages: explain who you help](/articles/financial-advisor-niche-service-pages); [Financial advisor podcasts: build useful transcript pages](/articles/financial-advisor-podcast-transcript-pages); [Financial advisor seminar pages: verify event details](/articles/financial-advisor-seminar-registration-page); [Financial advisor testimonials: review before publishing](/articles/financial-advisor-testimonials-website-review); [Financial advisor fees page: make the service clear](/articles/financial-advisor-website-fees-page); [Form 5500 participant counts: choose the right field before comparing plan size](/articles/form-5500-participant-counts-active-total-account-balances). [financial advisors](/for/financial-advisors): website and search resources. ## Related: financial advisors - [AI-native financial advisors: the first functions to build](/articles/ai-native-financial-advisors-first-functions) - [Financial advisor AI rules: data, approvals, and spend](/articles/financial-advisor-ai-rules-data-approvals-spend) - [Financial advisor award badges: verify the website claim](/articles/financial-advisor-awards-ratings-website) ---- ```text .|########||. .|########||. .|########||. |##||. .||##|. |##||. .||##|. |##||. .||##|. |#|. .|#|. |#|. .|#|. |#|. .|#|. |#| |#| |#| |#| |#| |#| .#| |#. .#| |#. .#| |#. .#. .#| .#. .#| .#. .#| |#. .#| |#. .#| |#. .#| |# ...... #| |# ...... #| |# ...... #| .# ||#########| #| .# ||#########| #| .# ||#########| #| .#. |######||######|. .#. .#. |######||######|. .#. .#. |######||######|. .#. #. .##|###|##|#|######| .# #. .##|###|##|#|######| .# #. .##|###|##|#|######| .# || |##|#||||||||||||#||#| || || |##|#||||||||||||#||#| || || |##|#||||||||||||#||#| || # |#||||||||||||||||||||#| #. # |#||||||||||||||||||||#| #. # |#||||||||||||||||||||#| #. || |#||||||||||||||||||||||#| || || |#||||||||||||||||||||||#| || || |#||||||||||||||||||||||#| || # .#||||||||||||||||||||||||#| # # .#||||||||||||||||||||||||#| # # .#||||||||||||||||||||||||#| # || ....|||#||||||##|#|||#|#||##||||....|. || || ....|||#||||||##|#|||#|#||##||||....|. || || ....|||#||||||##|#|||#|#||##||||....|. || #. . ....|# ....#||| ||| .#||| ....#. .# #. . ....|# ....#||| ||| .#||| ....#. .# #. . ....|# ....#||| ||| .#||| ....#. .# # . ||||#| .#####|| . .#| .#||| ||||# #. # . ||||#| .#####|| . .#| .#||| ||||# #. # . ||||#| .#####|| . .#| .#||| ||||# #. .| ||||| #. |#|||||. || #. |#||. .||||| || .| ||||| #. |#|||||. || #. |#||. .||||| || .| ||||| #. |#|||||. || #. |#||. .||||| || || |.... #. ....|#. |. ...|. ....|| || || |.... #. ....|#. |. ...|. ....|| || || |.... #. ....|#. |. ...|. ....|| || #. .||||||##||||||##||####|||||||#||||||#| .# #. .||||||##||||||##||####|||||||#||||||#| .# #. .||||||##||||||##||####|||||||#||||||#| .# # .||####|###########################|. # # .||####|###########################|. # # .||####|###########################|. # # .#||||||.#.|| # |. ..# #| #|||||#| # # .#||||||.#.|| # |. ..# #| #|||||#| # # .#||||||.#.|| # |. ..# #| #|||||#| # # .#|||||| .. |# ## |#| ...#|#|||#| # # .#|||||| .. |# ## |#| ...#|#|||#| # # .#|||||| .. |# ## |#| ...#|#|||#| # # .#|||#|# .# .#| #| ##|.#..#|||||#| # # .#|||#|# .# .#| #| ##|.#..#|||||#| # # .#|||#|# .# .#| #| ##|.#..#|||||#| # # .#||||||############|######|||||#| # # .#||||||############|######|||||#| # # .#||||||############|######|||||#| # # |...||#||||||#||||#|#||||||#|||||#||| |.| # # |...||#||||||#||||#|#||||||#|||||#||| |.| # # |...||#||||||#||||#|#||||||#|||||#||| |.| # #. .. ||||# .|||##|. |#| .|| || .|||#. #| # .# #. .. ||||# .|||##|. |#| .|| || .|||#. #| # .# #. .. ||||# .|||##|. |#| .|| || .|||#. #| # .# || | ...|| ...##| | #| .|. |. ##### .. .| || || | ...|| ...##| | #| .|. |. ##### .. .| || || | ...|| ...##| | #| .|. |. ##### .. .| || || ||||| || ||||#| . |. |. |#. ||||| |#| || || || ||||| || ||||#| . |. |. |#. ||||| |#| || || || ||||| || ||||#| . |. |. |#. ||||| |#| || || .# |.....#|....|#.||||.|||##.|#|....||.#||.#. #. .# |.....#|....|#.||||.|||##.|#|....||.#||.#. #. .# |.....#|....|#.||||.|||##.|#|....||.#||.#. #. #.|||||||#############################| ||| .# #.|||||||#############################| ||| .# #.|||||||#############################| ||| .# || ##||#||#||||||#||#||#||#||##. || || ##||#||#||||||#||#||#||#||##. || || ##||#||#||||||#||#||#||#||##. || # .#|||||||||#||#|||||||||||#| # # .#|||||||||#||#|||||||||||#| # # .#|||||||||#||#|||||||||||#| # || |#||||||||||||||||||||||#| || || |#||||||||||||||||||||||#| || || |#||||||||||||||||||||||#| || .# |#||||||||||||||||||||#| #. .# |#||||||||||||||||||||#| #. .# |#||||||||||||||||||||#| #. || |#||||||||||||||||||#| || || |#||||||||||||||||||#| || || |#||||||||||||||||||#| || #. .######|#|#########| .# #. .######|#|#########| .# #. .######|#|#########| .# .#. |#####||||#####| .#. .#. |#####||||#####| .#. .#. |#####||||#####| .#. |# ||########|| #. |# ||########|| #. |# ||########|| #. |# ...... #| |# ...... #| |# ...... #| |#. .#| |#. .#| |#. .#| |#. .#. |#. .#. |#. .#. .#| |#. .#| |#. .#| |#. |#| |#| |#| |#| |#| |#| .|#|. .|#|. .|#|. .|#|. .|#|. .|#|. |##||. .||##| |##||. .||##| |##||. .||##| .||########||. .||########||. .||########||. Scale With Search 2026 [scalewithsearch.com](https://scalewithsearch.com) ```