EFW2 Overview
The EFW2 format is the electronic file specification published by the Social Security Administration (SSA) for electronic W-2 filing. Employers and third-party submitters use the EFW2 specifications to create fixed-length record files that are uploaded to the SSA BSO (Business Services Online) portal for W-2 electronic submission. If your organization files Form W-2 wage and tax statements, understanding the EFW2 record layout is essential for compliant electronic filing.
The EFW2 format defines how employer, employee, wage, and tax data must be structured in a flat file — similar to how IRS Publication 1220 defines the W-2 e-file format equivalent for 1099 information returns filed through the IRS IRIS system or the FIRE system. Both are fixed-width ASCII formats with strict field positioning, but the EFW2 format is specific to W-2 and W-2c correction filings submitted to the SSA rather than the IRS.
W-2 Filing Threshold: Who Must Use the EFW2 Format?
The IRS and SSA require electronic W-2 filing if you are filing 10 or more W-2 forms for a tax year. This W-2 filing threshold was significantly lowered in recent years — previously set at 250, it now matches the same 10-return threshold used for 1099 forms and other information returns filed through the FIRE system or IRS IRIS portal.
Even if you file fewer than 10 W-2s, the SSA strongly encourages W-2 electronic submission through SSA BSO using the EFW2 format. Electronic submissions are processed faster, produce fewer errors, and give you immediate confirmation that your file was received. Employers who still rely on paper W-2 filings face longer processing times and a higher risk of missing the W-2 filing deadline. Before submitting, verify your employer and employee TIN information to avoid rejections.
Understanding the EFW2 Specifications and File Structure
The EFW2 specifications, formally titled "Specifications for Filing Forms W-2 Electronically (EFW2)", are published annually by the SSA. The document defines the exact EFW2 record layout, field positions, and validation rules for W-2 electronic submission. Key characteristics of the W-2 e-file format include:
- Fixed-width records: Each record type has a defined length of 512 characters. Every field occupies a specific character position within the record, and all records must be padded to exactly 512 characters.
- Hierarchical record structure: An EFW2 file contains multiple record types arranged in a strict hierarchy — Submitter Record (RA), Employer Record (RE), Employee Wage Records (RW/RO/RS), Total Records (RT/RU), State Totals (RV), and Final Record (RF).
- Numeric and alpha field rules: Dollar amounts are stored as whole numbers without decimal points or dollar signs. Alpha fields are left-justified and blank-filled. Numeric fields are right-justified and zero-filled.
- No delimiters or headers: Like the IRS Publication 1220 format used for FIRE system filings, EFW2 files contain no column headers, commas, or field separators — just continuous fixed-position data.
EFW2 Record Type Reference Table
The EFW2 record layout is built from nine record types, each identified by a two-character code. Every record is exactly 512 characters. The following table summarizes each record type, its purpose, and how many times it appears in a valid EFW2 file:
| Record Code | Record Name | Purpose | Occurrence per File |
|---|---|---|---|
| RA | Submitter Record | Identifies the entity submitting the file (EIN, company name, address, contact info). Required as the first record. | Exactly 1 |
| RE | Employer Record | Identifies each employer whose W-2 data follows (EIN, employer name, state ID). One per employer block. | 1 per employer |
| RW | Employee Wage Record | Core W-2 data for each employee — SSN, name, wages, federal/state tax withheld, Social Security and Medicare wages. | 1 per employee |
| RO | Employee Wage - Optional | Additional data that does not fit in RW — allocated tips, dependent care benefits, deferred compensation, Box 12 codes. | 0 or 1 per employee |
| RS | State Wage Record | State-specific wage and tax data. Required for combined federal/state filing or when reporting state wages. | 0 or more per employee |
| RT | Total Record | Aggregate totals for all RW records in the employer block. The SSA cross-checks these against individual records. | 1 per employer |
| RU | Total - Optional | Aggregate totals for all RO records in the employer block. Required only if RO records are present. | 0 or 1 per employer |
| RV | State Total Record | Summarizes state-level totals for all RS records in the employer block. | 0 or 1 per employer |
| RF | Final Record | Marks the end of the entire EFW2 file. Must be the last record. | Exactly 1 |
A minimal valid EFW2 file contains: RA → RE → RW → RT → RF. Files with multiple employers repeat the RE through RT/RU/RV block for each employer before the closing RF record.
EFW2 Record Types Explained
Below is a detailed explanation of each record type in the EFW2 record layout and how they work together in a valid W-2 e-file:
- RA — Submitter Record: Identifies the entity submitting the file (which may be different from the employer). Contains the submitter's EIN, company name, address, and contact information. Every EFW2 file begins with exactly one RA record.
- RE — Employer Record: Identifies each employer whose W-2 data follows. A single file can contain data for multiple employers if submitted by a third-party agent or payroll provider.
- RW — Employee Wage Record: Contains the core W-2 data for each employee — Social Security number, name, wages, federal tax withheld, Social Security wages, Medicare wages, and all the W-2 box amounts that appear on the printed form.
- RO — Employee Optional Record: Provides additional data fields that don't fit in the RW record, including allocated tips, dependent care benefits, and other compensation details.
- RS — State Wage Record: Reports state-specific wage and tax information. Required when state wages are reported and the state participates in combined federal/state filing.
- RT — Total Record: Contains the aggregate totals for all RW records within an employer block. The SSA uses this to verify data integrity.
- RU — Optional Total Record: Aggregates totals from RO records within an employer block.
- RV — State Total Record: Summarizes state-level totals for RS records.
- RF — Final Record: Marks the end of the file. Every EFW2 file must end with exactly one RF record.
SSA BSO: Business Services Online for W-2 Electronic Submission
SSA BSO (Business Services Online) is the SSA's web portal where employers and authorized submitters upload EFW2 files, check file status, and manage their W-2 electronic submissions. To use SSA BSO, you must:
- Register for a BSO account at the SSA's website
- Complete identity verification (individuals may need to verify through ID.me)
- Obtain authorization to submit W-2 files on behalf of your organization or clients
Once registered, you can upload your EFW2 file through the BSO portal. The system performs automated validation checks and returns a processing status. Files are typically processed within 1-2 business days. If errors are found, you will receive a detailed error report identifying the specific records and fields that need correction. Note that the SSA BSO portal handles W-2 and W-2c filings, while 1099 filings use the separate FIRE system or the newer IRS IRIS portal.
AccuWage Step-by-Step Testing Guide for EFW2 Files
The SSA provides a free testing tool called AccuWage that validates your EFW2 file against the current year's EFW2 specifications before you submit it through SSA BSO. Follow these steps to test your W-2 e-file before submission:
- Download AccuWage Online: Visit the SSA's Employer W-2 Filing Instructions and Information page and access AccuWage Online. The SSA retired the downloadable desktop version in favor of the web-based tool, which always uses the current year's EFW2 specifications.
- Log in to BSO: AccuWage Online requires a BSO account. Log in with your BSO credentials and navigate to the AccuWage testing tool from the main menu.
- Upload your EFW2 file: Select your EFW2 file from your local system. AccuWage accepts the same fixed-width format that BSO expects for final W-2 electronic submission.
- Review validation results: AccuWage scans every record in the file and reports errors by record type, record number, and field position. Errors are categorized as critical (file will be rejected) or warning (file may be accepted but data quality is questionable).
- Fix errors in your source data: Correct any issues identified — common problems include record length errors, invalid SSNs, and RT/RU total mismatches. Regenerate the EFW2 file from your payroll system or BoomTax.
- Re-test until clean: Upload the corrected file to AccuWage again. Repeat until AccuWage reports zero critical errors.
- Submit through BSO: Once AccuWage confirms the file is valid, navigate to the file upload section of BSO and submit the EFW2 file for official processing.
Running your file through AccuWage before uploading to SSA BSO is strongly recommended. It catches errors that would otherwise cause your file to be rejected, saving time and avoiding the need to resubmit before the W-2 deadline.
Common EFW2 Error and Rejection Codes with Fixes
When SSA BSO rejects an EFW2 file or flags specific records, it returns error codes that identify the problem. The following table lists common EFW2 rejection codes, their meaning, and how to fix them:
| Error Category | Description | Affected Record(s) | How to Fix |
|---|---|---|---|
| Invalid EIN | The employer identification number does not match IRS records or is formatted incorrectly. | RA, RE | Verify the EIN against your IRS CP 575 notice. Ensure the field is 9 digits, right-justified, and zero-filled. |
| Invalid SSN | An employee's Social Security number is missing, all zeros, or fails format validation. | RW | Confirm the SSN with the employee. Use TIN matching to verify before filing. Do not use placeholder values like 000-00-0000. |
| Record Length Error | One or more records are not exactly 512 characters. | Any | Check for extra line breaks, missing padding, or encoding issues (file must be ASCII). Ensure every record is blank-padded to 512 characters. |
| Total Mismatch | The RT or RU total records do not match the sum of the individual wage records. | RT, RU | Recalculate totals for all RW/RO records in the employer block. Ensure dollar amounts exclude decimals and are right-justified with zero-fill. |
| Missing Required Record | The file is missing an RA, RE, RT, or RF record. | File-level | Verify the file structure follows the required sequence: RA → RE → RW → RT → RF. Every employer block needs RE and RT records. |
| Invalid Record Sequence | Records appear out of order (e.g., RW before RE, or RT before all RW records). | File-level | Reorder records to follow the EFW2 hierarchy. Use AccuWage to pinpoint exactly which record breaks the sequence. |
| Invalid State Code | The state abbreviation in the RS record is not recognized. | RS | Use the official two-character FIPS state code as listed in the EFW2 specifications. Ensure the field is left-justified and upper case. |
| Duplicate Submission | A file for the same employer and tax year was already accepted. | RE | If corrections are needed, file a W-2c correction using the EFW2C format rather than resubmitting the original. |
| Invalid Tax Year | The tax year in the RE record does not match the current filing year accepted by BSO. | RE | Ensure the tax year field reflects the correct year (2025 for the current filing season). BSO only accepts the current and immediately prior tax years. |
Using BoomTax to generate your W-2 filings eliminates these common errors. The platform validates all data before generating the EFW2 file and handles the W-2 electronic submission to the SSA on your behalf.
EFW2 vs IRIS: Comparing W-2 Electronic Filing Methods
With the IRS expanding the Information Returns Intake System (IRIS) for 1099 filings, filers sometimes wonder whether W-2 forms can also be filed through IRIS. Here is how the two systems compare for electronic W-2 filing:
| Feature | EFW2 (SSA BSO) | IRIS (IRS) |
|---|---|---|
| Accepted Forms | W-2, W-2c (via EFW2C format), W-2AS, W-2GU, W-2VI | 1099 series only (1099-NEC, 1099-MISC, 1099-INT, 1099-DIV, etc.) |
| Filing Agency | Social Security Administration (SSA) | Internal Revenue Service (IRS) |
| File Format | Fixed-width ASCII (512 characters per record) per the EFW2 specifications | XML-based or manual entry via IRIS portal |
| Upload Portal | SSA Business Services Online (BSO) | IRIS Taxpayer Portal or TCC-enrolled application-to-application channel |
| Testing Tool | AccuWage (validates EFW2 file structure and data) | IRIS A2A testing environment for TCC holders |
| W-2 Support | Yes — this is the only accepted channel for electronic W-2 filing with the SSA | No — IRIS does not accept W-2 forms |
| Correction Filing | EFW2C format for W-2c corrections | Corrected 1099 returns filed through IRIS |
| E-File Threshold | 10 or more W-2 forms | 10 or more 1099 forms |
The key takeaway: W-2 forms cannot be filed through IRIS. The EFW2 format and SSA BSO remain the only electronic filing channel for W-2 wage statements. If you also file 1099 forms, you will use the FIRE system or IRS IRIS for those returns and SSA BSO for your W-2s. BoomTax handles both W-2 and 1099 filings from a single platform, submitting to the correct agency automatically.
W-2 Filing Deadlines for 2026
For tax year 2025, the W-2 filing deadlines are:
Recipient Copy Deadline: Monday, February 2nd, 2026
Employers must furnish copies of Form W-2 to employees by this date.
SSA E-File Deadline: Monday, February 2nd, 2026
Electronic W-2 submissions through SSA BSO using the EFW2 format are due on the same date as recipient copies.
This is different from most 1099 filing deadlines, where the
IRS e-file deadline is typically later than the recipient copy deadline.
Need more time? Submit Form 8809 through BoomTax to request a 30-day extension. Note that the employee copy deadline cannot be extended.
Penalties for Late or Incorrect W-2 Filings
The IRS imposes penalties for failure to file W-2 forms on time or for filing with incorrect information. For tax year 2025:
- $60 per form if filed within 30 days of the due date (maximum $683,000).
- $130 per form if filed more than 30 days late but by August 1 (maximum $2,049,000).
- $340 per form if filed after August 1 or not filed at all (maximum $4,098,500).
- $680 per form for intentional disregard (no maximum).
Small businesses with gross receipts of $5 million or less qualify for reduced maximum penalties: $239,000, $683,000, and $1,366,000 respectively.
E-File W-2 Forms with BoomTax
Building EFW2 files from scratch is technically demanding and error-prone. Rather than wrestling with fixed-width EFW2 record layouts and AccuWage validation errors, BoomTax handles the entire electronic W-2 filing process for you:
- Import your payroll data — upload via CSV, spreadsheet, or enter data directly in the platform.
- Validate before submission — BoomTax checks for missing SSNs, EIN mismatches, and wage discrepancies before generating the filing. Use TINCorrect to verify TINs in bulk.
- E-file with the SSA — BoomTax generates the compliant EFW2 file and submits it electronically to SSA BSO on your behalf.
- Print and deliver employee copies — Generate printable W-2 forms for distribution to employees, or deliver them electronically.
- File corrections if needed — If you discover errors after filing, e-file W-2c corrections using the EFW2C format directly from BoomTax.
- Request extensions — Need more time? File Form 8809 for an automatic 30-day extension.
If your existing payroll software already generates EFW2 files, BoomTax can also import those files directly — just drag and drop. BoomTax parses the fixed-width records, validates the data against the current EFW2 specifications, and handles the W-2 electronic submission, so you don't have to navigate SSA BSO yourself.
The EFW2 format remains the standard for electronic W-2 filing with the SSA. Whether you are a small employer filing a handful of W-2s or a payroll service bureau processing thousands, understanding the EFW2 specifications and using the right tools ensures your filings are accepted on the first attempt. Let BoomTax handle the complexity of EFW2 formatting, AccuWage validation, and W-2 electronic submission so you can focus on running your business.
