OSHA 300a vs OSHA 300: What's the Difference?

OSHA 300a vs OSHA 300: What’s the Difference?

For safety professionals, OSHA recordkeeping can feel like a maze of forms, deadlines, and submission rules. Two of the most commonly confused documents are the OSHA 300 log and the OSHA 300A summary.

Although they are closely related, they serve very different purposes and have different posting and submittal requirements under 29 CFR 1904. Misunderstanding these differences can lead to missed deadlines, compliance gaps, or even OSHA citations.

In this guide, we’ll break down:

The key differences between the OSHA 300 log and OSHA 300A summary
Who must complete and post each form
Posting vs. electronic submission requirements
What Appendix A and Appendix B really mean
Common compliance pitfalls

What is the OSHA 300 log?

Think of the OSHA 300 log as your detailed incident ledger for the year. The OSHA 300 log is the ongoing, internal record of work-related injuries and illnesses at your establishment.

It includes:

Employee name
Job title
Date of injury or illness
Description of the incident
Classification (death, days away, job transfer, etc.)
Number of days away or restricted
Whether the case involved an injury, skin disorder, respiratory condition, etc.

Key characteristics of the OSHA 300 Log:

Updated within 7 calendar days of a recordable incident
Not publicly posted
Must be kept on file for five years
Only submitted electronically for certain employers under Appendix B

What is the OSHA 300a summary?

The OSHA 300A summary is a year-end summary of the totals from your OSHA 300 log. Unlike the OSHA 300 log, the OSHA 300A summary must be posted and, for some employers, electronically submitted to OSHA.

Instead of listing individual employee case details, it shows:

Total number of deaths
Total number of injury and illness cases
Total days away from work
Total job transfers or restrictions
Types of injuries and illnesses
Average number of employees
Total hours worked

OSHA 300A Posting Requirements (29 CFR 1904.32)

One of the most important compliance rules to understand is posting vs. submission. Establishments with 10 or more employees during the calendar year must physically post the OSHA 300A summary (not the OSHA 300 log). Smaller companies may still be required to post if OSHA specifically requests it.

When it comes to the posting timeline, OSHA is very clear. From 29 CFR 1904.32(b)(6): “When do I have to post the annual summary? You must post the summary no later than February 1 of the year following the year covered by the records and keep the posting in place until April 30.”

Who Must Submit Electronically?

Under 29 CFR 1904.41(a)(1)(i):

“If your establishment had 20–249 employees at any time during the previous calendar year, and your establishment is classified in an industry listed in appendix A to subpart E of this part, then you must electronically submit information from OSHA Form 300A Summary of Work-Related Injuries and Illnesses to OSHA or OSHA’s designee. You must submit the information once a year, no later than the date listed in paragraph (c) of this section of the year after the calendar year covered by the form.”

Additionally, establishments with 250+ employees must also submit electronically. The electronic submission deadline is March 2 (each year for the previous year’s data).

Appendix A vs Appendix B: Why It Matters

This is one of the most misunderstood parts of OSHA log submittal requirements.

Appendix A (Subpart E)

Lists industries required to submit OSHA 300A data only
Applies to establishments with 20–249 employees

Appendix B (Subpart E)

Lists industries required to submit OSHA 300, 300A, and 301 data
Applies to certain higher-risk industries
These employers submit more detailed injury data

Many employers mistakenly submit the wrong forms—or fail to submit when required—because they don’t verify which appendix applies to their NAICS code.

If you’re unsure whether your establishment must post, submit, or certify OSHA log, or if you want a second set of eyes on your OSHA 300 and 300A forms, professional guidance can save time and prevent costly mistakes.

A compliance review or recordkeeping audit can help ensure your OSHA logs are accurate, complete, and fully aligned with 29 CFR 1904 requirements.

Authored by: Tim Neubauer, January 2026