Comparison · 2026

OASIS-E1 vs OASIS-E2: A Side-by-Side Comparison

A clear, structured comparison of OASIS-E1 and OASIS-E2, what stayed the same, what changed, when each took effect, and what your agency needs to do to transition without payment leakage.

Key Takeaways

  • →OASIS-E2 has been in effect since April 1, 2026. It builds on OASIS-E1 (effective Jan 2025), itself an iteration of OASIS-E (effective Jan 2023).
  • →Structural framework preserved: time points, M-items, Section GG, PDGM functional items, HH QRP submission via iQIES.
  • →What changed: O0350 removed, A1255 Transportation and A0810 Sex replace older items, Language, Hearing, and Vision added at ROC, J1900 revised, plus Q&A coding tips.
  • →Biggest transition risk: the new fall definition in J1800 and M1033. M1033 is one of the PDGM functional items.
  • →OASIS-E1 workflows update incrementally, no rebuild needed; refresh QA rules and clinician training on the items that actually changed.

Quick Reference Comparison

Dimension OASIS-E1 OASIS-E2
Effective Date January 1, 2025 April 1, 2026
Replaces OASIS-E (Jan 2023) OASIS-E1
Structural Framework 5 time points · M-items · GG-items Same (preserved)
Section GG (Functional) Discharge Goal column removed (Jan 1, 2025) Same activities and scale. New Q&A coding tips
Cognitive / Behavioral BIMS, PHQ-2/9, behavior items Same instruments. Revised PHQ and pain interview instructions
Social Items A1250 Transportation (SOC, ROC, DC), B1300 Health Literacy, D0700 Social Isolation A1255 Transportation (SOC, ROC). No housing, food, or utilities items
PDGM Mapping Claim diagnoses set clinical group and comorbidity. M1800-M1860 and M1033 set functional level Same. New fall definition affects M1033
HH QRP Submission iQIES; required time points Same submission requirements
EMR Vendor Updates Pushed automatically by HCHB, WellSky, etc. Same, pushed automatically by EMR vendors

What Stayed the Same

OASIS-E2 is an iterative update, so the foundational architecture is preserved:

  • Five required time points: SOC, ROC, Recertification, Transfer, Discharge
  • M-item structure across clinical, functional, and service utilization domains
  • Section GG functional assessment framework
  • PDGM functional items (M1800-M1860 and M1033) and their response options
  • Home Health Quality Reporting Program (HH QRP) submission requirements via iQIES
  • Star Ratings methodology
  • Conditions of Participation (CoP) compliance requirements

This means existing OASIS-E1 clinician workflows, EMR forms, and QA processes can be updated incrementally rather than rebuilt from scratch.

What Changed in OASIS-E2

  1. Item removed. O0350 Patient's COVID-19 Vaccination Is Up to Date.
  2. Items replaced. A1250 Transportation became A1255, asked about the past 12 months at SOC and ROC only. M0069 Gender became A0810 Sex.
  3. Items added to ROC. A1110 Language, B0200 Hearing, and B1000 Vision.
  4. Falls. Revised J1900 injury descriptions and a new fall definition for J1800 and M1033.
  5. SDOH items not added. The CY 2025 final rule adopted Living Situation, two Food items, and Utilities. The CY 2026 final rule removed them before collection began, so OASIS-E2 has no housing, food, or utilities items.
  6. Q&A guidance. New coding tips for Section GG, M1840, M1311, pain, PHQ, and administrative items. The GG discharge goal had already been removed with OASIS-E1.
  7. Updated CMS guidance. The CMS OASIS-E2 Guidance Manual supersedes the OASIS-E1 manual for all assessments completed on or after the effective date.

For full item-level detail, see What Changed in OASIS-E2: Item-by-Item Guide.

OASIS-E2 Updates Since Go-Live

  • July 2026 Q&As override the manual on two items. CMS's July 2026 OASIS Q&As revised guidance for M1060 (height and weight) and M1311 (unhealed pressure ulcers and injuries by stage), and the Q&A answers supersede the OASIS-E2 Guidance Manual for those items. Update your QA rules and clinician tip sheets.
  • All-payer OASIS counts toward HH QRP compliance from 2027. For patients with a start of care on or after January 1, 2027, OASIS data for non-Medicare and non-Medicaid patients counts in the HH QRP Annual Payment Update compliance calculation.
  • Shorter submission deadlines are proposed. The CY2027 home health proposed rule (released July 1, 2026) would replace the 4.5-month OASIS submission window with a deadline on the 15th day of the second month after each quarter ends, starting with the CY2027 HH QRP. The final rule is not out yet as of October 6, 2026.

Sources: CMS OASIS Data Sets, LeadingAge summary of the July 2026 OASIS Q&As, CY2027 HH PPS proposed rule (91 FR 41216), CY2026 HH PPS final rule fact sheet.

PDGM Payment Impact: What to Watch

OASIS-E2 did not change the PDGM functional items' response options. The functional level still comes from points on M1800-M1860 and M1033, and Section GG earns no PDGM points. The E2 change with payment reach is the new fall definition in M1033. Separately, CMS recalibrates functional points and thresholds every January through rulemaking, which can shift payment patterns on its own.

During the first 60–90 days of OASIS-E2, agencies should:

  • Compare average PDGM payment per 30-day period to the 90-day pre-OASIS-E2 baseline
  • Identify clinicians whose functional impairment scoring shifts dramatically
  • Run focused QA on M1033 fall coding and M1800-M1860 scoring during the first 30 days
  • Provide just-in-time feedback to clinicians on scoring drift

For real-time PDGM-aware scoring guidance, see Lime's OASIS-E2 ambient scribe.

Transition Plan: From OASIS-E1 to OASIS-E2

  1. Week -8: Capture baseline metrics (PDGM payment, error rates, time-to-completion)
  2. Week -6: Confirm EMR vendor OASIS-E2 form push timeline
  3. Week -4: Update written OASIS policies and QA rule sets
  4. Week -3: Begin clinician training on OASIS-E2 changes (see 90-day training plan)
  5. Week 0: OASIS-E2 effective date, clinicians complete first assessments with QA co-signing
  6. Weeks 1–4: Daily QA huddles, weekly PDGM payment monitoring
  7. Weeks 5–12: Move to weekly QA review; complete competency validation
  8. Week 13: Full independent practice; quarterly internal audits begin

For the complete agency rollout playbook, see OASIS-E2 Implementation Playbook.

Related OASIS-E2 Resources

OASIS-E1 vs OASIS-E2, FAQ

What's the difference between OASIS-E1 and OASIS-E2?
OASIS-E2 is a minor revision of OASIS-E1. It removes O0350 COVID-19 vaccination status, replaces A1250 Transportation with A1255 (SOC/ROC only) and M0069 Gender with A0810 Sex, adds A1110 Language, B0200 Hearing, and B1000 Vision to Resumption of Care, revises the J1900 fall injury descriptions, and adds coding tips from the OASIS Q&As. The structural framework, five required time points, M-item architecture, PDGM payment mapping, and HH QRP submission requirements, remains intact. OASIS-E2 is an iterative update, not a wholesale rewrite, which means existing OASIS-E1 workflows can be updated incrementally rather than rebuilt.
When did OASIS-E1 take effect vs OASIS-E2?
OASIS-E1 took effect January 1, 2025, replacing the original OASIS-E (which was effective January 1, 2023). OASIS-E2 took effect April 1, 2026. CMS posted the final OASIS-E2 instruments and change table on February 26, 2026, and the July 2026 OASIS Q&As already supersede the OASIS-E2 Guidance Manual for M1060 and M1311.
Can I keep using OASIS-E1 forms after OASIS-E2 takes effect?
No. Once OASIS-E2 is the active version per CMS guidance, all submitted assessments must be on the OASIS-E2 form. Most home health EMR vendors (HCHB, WellSky, MatrixCare, Axxess, DSL) push the form update automatically. Agencies that submit on the prior version after the effective date will receive submission errors and risk Quality Reporting penalties.
Will OASIS-E2 affect my PDGM payment?
Only indirectly. The PDGM functional impairment level still comes from M1800-M1860 and M1033, and their response options did not change. Section GG does not earn PDGM points. The clinical group and comorbidity adjustment still come from the diagnoses on the claim. The E2 change to watch is the new fall definition, which affects M1033 Risk for Hospitalization. Agencies should monitor PDGM payment trends weekly during the first 60–90 days of OASIS-E2 to identify any unexpected payment shifts and respond quickly.

Transition to OASIS-E2 without payment leakage.

See OASIS Scribe