5,000 claims checked against the CMS Web Pricer
How close our inpatient (IPPS) prices come to CMS’s own pricer, claim by claim: synthetic claims at real hospitals, each priced by both, every difference counted and the full file to download.
The result
5,000 synthetic inpatient claims at 60 real hospitals were priced twice, by our engine and by the CMS Web Pricer, each on the hospital’s provider record in force on the discharge date; the CMS Web Pricer got one claim at a time. Every one came back within one dollar of the other. Without the per-diem pass-through, which every figure on this page leaves out unless it says so, the CMS Web Pricer’s totals for these claims add up to $88,981,916; the claim-by-claim differences net to −$9.64.
What the set covers
The result above is for inpatient claims under the inpatient prospective payment system (IPPS) only. Skilled nursing, home health, outpatient, professional, post-acute and Medicaid prices were not part of this comparison.
- MS-DRGs
- 82distinct, of the 770 in version 43 and the 766 in version 44
- Hospitals
- 60real IPPS hospitals, each on its own provider record
- FY2026 discharges
- 2,500 to
- FY2027 discharges
- 2,500 to
10 discharge statuses tested, with the number of claims for each:
01Home or self-care2,46303Skilled nursing facility96106Home with home health care95662Inpatient rehabilitation facility12502Transfer to another acute hospital12220Died11307Left against medical advice10450Hospice, at home8451Hospice, in a facility4163Long-term care hospital31
How far apart the two totals were
Every claim, by the size of the difference between our total and the CMS Web Pricer’s, in either direction. 2,015 were higher on our side, 2,337 lower, 648 equal.
By fiscal year
Each claim is priced on the rates and the hospital record in force on its discharge date.
| Fiscal year | Claims | Within $1.00 | Exact to the cent | Within 5 cents | Largest difference |
|---|---|---|---|---|---|
| FY2026 discharges 2025-10-01 to 2026-09-30 | 2,500 | 2,500 100% | 446 | 2,362 | $0.17 |
| FY2027 discharges 2026-10-01 to 2026-10-20 | 2,500 | 2,500 100% | 202 | 2,104 | $0.22 |
| All claims | 5,000 | 5,000 100% | 648 | 4,466 | $0.22 |
Transfers and outliers
The harder cases: a stay cut short by a transfer can be paid a per diem instead of the full DRG, and a very costly stay earns a cost outlier on top. The CMS Web Pricer’s return code says how it paid each claim.
| Case | Claims | Within $1.00 | Exact to the cent | Within 5 cents | Largest difference |
|---|---|---|---|---|---|
| Paid as a transfer by the CMS Web Pricer | 298 | 298 100% | 55 | 279 | $0.21 |
| Transfer discharge, full DRG paid (stay too long for the per diem) | 1,673 | 1,673 100% | 204 | 1,512 | $0.22 |
| Cost outlier paid by the CMS Web Pricer | 165 | 165 100% | 14 | 108 | $0.18 |
| No transfer and no outlier | 2,932 | 2,932 100% | 381 | 2,615 | $0.22 |
Our engine paid a cost outlier on 165 claims and the CMS Web Pricer on 165; the two agree on outlier or no outlier for 5,000 of 5,000. 1,971 claims have a discharge status the transfer rule applies to; the CMS Web Pricer paid 298 of them as transfers.
By discharge status
Where the patient went when they left the hospital, as coded on the claim.
| Discharge status | Claims | Within $1.00 | Exact to the cent | Within 5 cents | Largest difference |
|---|---|---|---|---|---|
| Home or self-care 01 | 2,463 | 2,463 100% | 306 | 2,163 | $0.21 |
| Skilled nursing facility 03 | 961 | 961 100% | 106 | 876 | $0.21 |
| Home with home health care 06 | 956 | 956 100% | 141 | 858 | $0.22 |
| Inpatient rehabilitation facility 62 | 125 | 125 100% | 14 | 113 | $0.21 |
| Transfer to another acute hospital 02 | 122 | 122 100% | 31 | 119 | $0.09 |
| Died 20 | 113 | 113 100% | 17 | 95 | $0.22 |
| Left against medical advice 07 | 104 | 104 100% | 13 | 99 | $0.07 |
| Hospice, at home 50 | 84 | 84 100% | 12 | 80 | $0.09 |
| Hospice, in a facility 51 | 41 | 41 100% | 6 | 40 | $0.06 |
| Long-term care hospital 63 | 31 | 31 100% | 2 | 23 | $0.19 |
What was compared
The total Medicare pays the hospital for the stay, before the patient’s deductible and coinsurance and before sequestration. The headline compares the totals without the per-diem pass-through: a per-day amount from the hospital’s provider record for costs Medicare pays outside the DRG rate, which the CMS Web Pricer reports alongside its total. So it is the CMS Web Pricer’s total less its pass-through, against our total without it.
Counted with the pass-through on both sides, 5,000 of 5,000 claims are within $1.00 and 648 are exact to the cent; the largest difference is $0.22.
How the check was run
- Synthetic claims, no patient data. No real patient, member or claim is in the set. Ages, dates, diagnoses, procedures, lengths of stay and charges were generated at random by a program.
- Real hospitals. 60 hospitals that Medicare pays under the inpatient prospective payment system, with their real provider numbers, so every claim is priced on a real hospital’s payment factors.
- Both fiscal years. 2,500 discharged in FY2026, 2,500 discharged in FY2027.
- The same claim to both pricers. Each claim went to the CMS Web Pricer, one claim at a time, with the full hospital provider record in force on its discharge date; our engine priced the same claim on its own copy of that hospital’s record for the same date.
- When and which version. Run on October 23, 2026, our engine at commit
661891ba; CMS Web Pricer calculation versions 2026.1 and 2027.0.
Claims that missed
None. Every one of the 5,000 claims came back within $1.00.
Check it yourself
Every claim and the difference between the two totals: 5,000 rows. Columns: claim_id, fiscal_year, drg, ccn, los, covered_charges, discharge_date, discharge_status, cms_total, ours_total, diff, match. Both totals are shown for the MS-DRGs anyone can price here without a key; for the others the two totals are left blank and the difference and match remain. Totals exclude the per-diem pass-through, the same basis as the headline and its total; match is yes when the two are within $1.00.
To re-run one, open Verify vs CMS with the claim’s DRG, hospital, length of stay, charges and discharge date: it sends the claim to the CMS Web Pricer and to our engine and shows both, component by component.
Press release
November 2, 2026: PayerParity Publishes 5,000-Claim Test Against the CMS Web Pricer: Every Inpatient Claim Within $1.00, Largest Gap 22 Cents (PRWeb).