If you run a home health agency, you’ve probably heard of OASIS—and maybe even lost sleep over it.
OASIS is more than just a bunch of forms. It’s the foundation for how care is planned, documented, and reimbursed in home health. When done right, it supports high-quality care and ensures you get paid for your work. When done wrong, it’s a recipe for audits, penalties, and lost revenue.
At The Home Health Consultant (THC), we’ve spent over 20 years helping agencies like yours navigate Medicare regulations. We're more than familiar with OASIS. We want to help you tackle your submissions with confidence.
In this article, you’ll discover how OASIS works, what kind of data OASIS collects, and exactly when OASIS collects this data. Whether you’re a home health professional or just curious, we’ve got you covered.
What is OASIS?
OASIS stands for Outcome and Assessment Information Set. It’s a set of forms used to assess home health patients and track their progress. If your agency admits Medicare patients, completing OASIS assessments at specific points in their care is a must. This rule comes straight from Medicare’s Conditions of Participation (CoPs).
Each milestone in a patient’s care has a deadline for both:
- completing the OASIS form
AND
- submitting the OASIS data through the IQIES portal
Staying on top of these deadlines is key to compliance and timely reimbursement.
OASIS forms are long—really long. They include a mix of fill-in-the-blank and multiple-choice questions. These forms serve two big purposes:
- They help Medicare calculate your payments for each patient’s episode of care.
- They provide data to CMS, which is used to determine things like OBQI reports and your Star Ratings.
But there’s a catch. OASIS alone doesn’t meet Medicare’s CoP requirement for a full patient assessment. To stay compliant, agencies use forms and software vendors that build on OASIS with additional assessment questions. That’s why some OASIS forms end up being 40 pages (or more!), depending on your vendor.
Beyond payments and stats, OASIS is also an important clinical tool. It helps shape the care plan for each patient’s episode. Later assessments track progress, ensuring treatment stays on course and goals are met.
When Do You Fill Out OASIS?
OASIS assessments happen at key points in a patient’s care journey:
- Start of Care (SOC): This is the first big evaluation, done within five days of the patient’s first visit.
- Recertification: Every 60 days, you check in to see if and what care is still needed. This form must be completed in the last five days of the episode.
- Significant Change: If a patient’s condition improves or declines significantly, you’ll update their OASIS.
- Transfers: When a patient moves to another type of care, like a hospital or rehab facility but is not discharged from your services.
- Discharge (DC): The final assessment when care ends.
See the chart below for a more in-depth look at when to collect OASIS data. The information in this chart comes directly from the CMS OASIS E-1 Manual. This information is accurate as of February 4th, 2025.
Each of these points are a chance to capture crucial information about the patient. That data doesn’t just stay in your files. It’s uploaded to CMS’s national database to evaluate your agency’s quality metrics.
Who Can Fill Out OASIS?
Not just anyone can complete an OASIS assessment. It’s important to make sure you’re sending the right kind of evaluation level-clinician to avoid problems down the line.
Each OASIS form (SOC, RC, and DC) has four options for the ‘Discipline of Person Completing Assessment.’ On the form this appears as item M0080. The four choices for ‘discipline of person’ include:
- Registered Nurse (RN)
- Physical Therapist (PT)
- Speech-Language Pathologist/Speech Therapist (SLP/ST)
- Occupational Therapist (OT)
You can find an example of what this looks like on the OASIS E-1 All Items Form (provided by CMS) below:
Registered nurses (RNs) are most commonly responsible for completing OASIS assessments. However, some exceptions apply.
For example, let’s say you have a patient where the only skilled care ordered is physical therapy. In this case, a physical therapist (PT) can complete OASIS. This exception also applies for speech-language pathologists (SLP).
The fourth option, OT, is a bit of a special case. Occupational therapy alone does not qualify a patient for Medicare. So, occupational therapists can only complete the assessment for Medicare patients when the order includes another qualifying therapy service (SLP or PT).
It’s important to know who’s qualified to handle each type of OASIS. Sending the wrong clinician could mean rejected submissions and delayed payments.
Who Cannot Complete OASIS Assessments?
There are a few positions which are unable to complete OASIS under any circumstances. These positions are:
- Licensed Practical/Vocational Nurses (LPNs/LVNs)
- Medical Social Workers (MSWs)
- Home Health Aides (CHHAs)
- Therapy Assistants (PTAs, COTAs, SLPAs)
Why OASIS Matters for Care Planning
OASIS isn’t just a bureaucratic hurdle; it’s the backbone of your care plans. Here’s how it works:
- Data Collection: Clinicians gather head-to-toe details about the patient. They also compile medication lists and diagnoses.
- Coding: Agencies (or external coding companies) use this data to determine the primary diagnosis for treatment. Keep in mind, this isn’t always the patient’s main condition—it’s the condition you’re treating.
- Care Plan Creation: Based on OASIS assessment data, you decide which disciplines (skilled nursing, PT, OT, speech therapy) will see the patient, what they’ll do, and how long it should take to meet their goals. The care plan is then approved by the physician.
Without accurate OASIS data, your care plans won’t meet CMS’s standards—and your reimbursements will take a hit.
The Consequences of Non-Compliance with OASIS
Let’s talk about what happens when OASIS submissions don’t go as planned. Missed deadlines or inaccurate data can lead to:
- Reduced Reimbursements: If submissions are late, payments may be withheld based on how late they are, potentially resulting in $0 reimbursement for that claim. If you wait more than 30 days, you’ll lose the claim entirely.
- Audits and Penalties: Non-compliance puts your agency under CMS’s microscope. Fines, audits, and even sanctions can follow.
- Reputation Damage: OASIS data feeds into your star ratings. Low ratings can drive patients and referral sources elsewhere.
Why Star Ratings Matter & Where OASIS Comes In
CMS star ratings are a big deal. They’re public-facing and used by patients to compare agencies. A low rating can scare off referrals and make it hard to compete. And the worst part? You might not even know why your rating dropped until it’s too late. Staying on top of OASIS compliance is the best way to protect your reputation.
What Are the Most Common Challenges With OASIS and How Can You Overcome Them?
No agency is flawless, but that shouldn’t stop you from aiming for excellence. Mistakes are inevitable, but being prepared can make all the difference. Below, we’ve outlined some of the most common OASIS-related mistakes agencies face—and how you can avoid them.
- Data Accuracy
- Challenge: Incomplete or incorrect data can lead to penalties.
- Solution: Invest in and maintain staff training to ensure accurate documentation
- Technology Integration
- Challenge: Systems that don’t communicate efficiently with CMS databases
- Solution: Confirm softwares are Use certified software compatible with CMS guidelines, and include in the software vendor contract that non-compatibility is cause for contract cancelation
- Keeping Up With Changes
- Challenge: Frequent updates to OASIS forms and protocols
- Solution: Stay informed with CMS updates and industry webinars, or hire a consultant for compliance guidance
What Role Does OASIS Play in the Home Health Industry?
OASIS forms collect detailed data about your patients, including:
- health conditions
- functional abilities
- living situations
This information goes directly to the Centers for Medicare & Medicaid Services (CMS), where it’s used to evaluate your performance. The better your data, the better your agency looks—and the better your star ratings and reimbursements.
OASIS data drives everything. It’s how you create care plans, measure outcomes, and stay compliant with Medicare regulations. It also helps determine how much you get paid, both for each individual claim, and annually under Value Based Purchasing. CMS uses aggregate OASIS data to calculate reimbursement rates, tying payments to the quality of care you provide.
What’s New with OASIS in 2025?
OASIS isn’t just about following rules; it’s about delivering better care and growing your agency. When you prioritize accuracy and compliance, you’re not just meeting requirements—you’re building a stronger, more successful agency.
OASIS isn’t going anywhere, and CMS keeps raising the bar. In 2025, new updates are rolling out that could affect how your agency operates. Now is the time to review your processes, train your team, and make sure your software is up to date. To find out how OASIS is changing this year, check out our article ‘What are the 2025 Mandatory OASIS Updates?’
*This article was written in consultation with Mariam Treystman.
Disclaimer: The content provided in this article is not intended to be, nor should it be construed as, legal, financial, or professional advice. No consultant-client relationship is established by engaging with this content. You should seek the advice of a qualified attorney, financial advisor, or other professional regarding any legal or business matters. The consultant assumes no liability for any actions taken based on the information provided.
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