ResidencyCAS vs ERAS: Which Specialties Use Each (2027)

ResidencyCAS vs ERAS: Which Specialties Use Each

Two specialties use ResidencyCAS instead of ERAS for the 2026-27 cycle: Emergency Medicine and Obstetrics & Gynecology. Every other specialty still applies through AAMC ERAS. ResidencyCAS is the application platform — the ERAS equivalent — not a different Match. If your specialty is on ResidencyCAS, you still register with the NRMP and match on the same Match Day. The single biggest change is the personal statement: ResidencyCAS gives every program in your specialty the same statement, with no per-program tailoring allowed.

Verified for the 2026-27 application cycle (2027 Match) as of July 2026. The specialty roster is the highest-staleness item on this page — re-verify against ECFMG and ResidencyCAS each cycle.

If your specialty is still on ERAS, nothing about your workflow changes and you can go straight to the ERAS personal statement length, format, and examples guide. If you are one of the two specialties that moved, the mechanics below — especially the single-statement rule — change how you should write. For the full month-by-month calendar either way, see the 2027 ERAS timeline and key dates.

Is my specialty on ERAS or ResidencyCAS? The 30-second answer

For the 2026-27 cycle, the split is short:

That is the entire list. OB/GYN and Emergency Medicine file through ResidencyCAS; internal medicine, surgery, pediatrics, family medicine, psychiatry, radiology, anesthesiology as a standalone specialty, and every other field still file through ERAS. ECFMG, which handles document uploads for international applicants, confirms the same two participating specialties.

"But I saw Aerospace Medicine on the ResidencyCAS list"

The ResidencyCAS applicant page lists more than two program lines because Emergency Medicine carries its combined tracks onto the platform with it: EM/Family Medicine, EM/Internal Medicine, EM/Pediatrics, EM/Anesthesiology, and EM/Aerospace Medicine. These are combined Emergency Medicine residency tracks, not separate specialties leaving ERAS. Standalone Aerospace Medicine — a preventive-medicine subspecialty — has not independently moved to ResidencyCAS. If you see "Aerospace Medicine" on the list, it is the EM/Aerospace Medicine combined track riding the EM platform, nothing more. There are two specialties on ResidencyCAS, not three.

What is ResidencyCAS, and why did two specialties leave ERAS?

ResidencyCAS does the same job ERAS does: it collects your application materials and delivers them to the residency programs you apply to. It is built by Liaison International — the company behind the centralized application services many physicians already used in medical school (AMCAS-adjacent CAS systems) — in partnership with the specialty societies. For OB/GYN, that partnership runs through ACOG, APGO, and CREOG; for Emergency Medicine, through CORD.

The adoption order matters because it is frequently reported backwards. OB/GYN went first. ResidencyCAS was announced in July 2023, and OB/GYN hosted its applications on the platform for the first time in the 2024-25 cycle — more than 2,400 applicants that first year, per ACOG. Emergency Medicine joined second, for the 2025-26 cycle; CORD's board confirmed in 2026 that "Emergency Medicine successfully completed its first application cycle utilizing ResidencyCAS." Both specialties continue on ResidencyCAS for 2026-27.

The stated reasons for moving are cost and specialty control over the application's data and workflow. CORD reported that Emergency Medicine's first ResidencyCAS cycle produced "nearly $780,000 in collective savings" for applicants and positioned the platform as cheaper than the ERAS application. Treat that figure as EM-specific and first-cycle, not a permanent guarantee — fees change per cycle (see below).

ResidencyCAS vs ERAS: the differences that change how you apply

Most rows are near-identical — same season, same submission day, same program-access day, same Match. The one row that genuinely changes your work is the personal statement.

The one that matters: a single personal statement to every program

This is the difference incumbent explainers skip, and it is the one that should shape your writing. Liaison's applicant help center states it plainly:

"You'll submit one personal statement per specialty, and it will be shared with all programs in that specialty."

"You cannot personalize this statement for individual programs."

The AMA frames the intent the same way: under ResidencyCAS each applicant submits "one personal statement that will go to all programs to which they apply," designed to "free students from the time-consuming — and often ineffective — practice of tailoring multiple versions."

How this differs from ERAS

If you have been reading ERAS advice, you arrived with the opposite mental model. In MyERAS you may create unlimited personal statements and assign a different one to each program — one statement assignable per program. That flexibility is gone on ResidencyCAS: one statement per specialty, delivered to every program in it, with no per-program version. It is the single sharpest difference between the two platforms.

What it changes about how you write it

When one essay goes to all your programs with zero tailoring, the writing target shifts. The statement can no longer flatter a specific program or name-drop a particular faculty member — every sentence has to survive being read by twenty or more programs at once. That pushes the essay toward being broadly true and specialty-defining: why this specialty, what you bring to it, and evidence a reader at any program in the field would find credible. Liaison is explicit that customizing statements per program "is not worth the time and effort," and points applicants to the Program Signals feature — not the essay — as the sanctioned way to express interest in specific programs.

That is a writing-strategy claim, and it is exactly what a rubric-style read is for. Whichever platform your specialty uses, the residency personal statement rubric checks the same things a program reader looks for: a clear specialty rationale, selected evidence that earns its space, and a statement that reads as genuinely the applicant's own. If you want to see what a single, no-tailoring statement should do line by line, work through the annotated residency personal statement examples before you draft.

Character limit

The ResidencyCAS statement cap is widely reported as roughly 4,000 characters (community advising guides and specialty sources state this figure). Liaison's essay page confirms that a maximum character count is enforced and shown live as you type, but does not print the digit in its help text — so treat 4,000 as reported and corroborated by secondary sources, not locked to a primary Liaison quote. Re-verify the exact number against the live application before you rely on it. For scale, if 4,000 holds, it is close to the ERAS one-page reader norm (~4,000-5,300 characters) baked in as a hard limit — a much tighter budget than the 28,000-character ERAS system ceiling, which was never a writing target anyway.

Applying to two specialties, or hedging with a backup

Because only two specialties are on ResidencyCAS, applicants who hedge across specialties can end up on both platforms at once.

• EM or OB/GYN alone: one platform (ResidencyCAS), one statement for the specialty, register separately for the NRMP Match.
• EM plus a specialty still on ERAS (for example internal medicine, family medicine, or standalone anesthesiology as a backup): the AMA is explicit that you "will need to complete two applications." In practice that means two platforms — ResidencyCAS for EM, ERAS for the backup — and two personal statements: the shared ResidencyCAS statement for your EM programs, plus a separate ERAS statement you can still assign per program in the ERAS style. The AMA reports that only around 5% of matched-EM U.S. MD graduates also applied to another specialty, so this is a real but minority case.
• EM plus an EM-combined track (for example EM and EM/Internal Medicine): both live on ResidencyCAS, but each counts as a separate specialty for statement assignment — so you may write more than one statement, all within ResidencyCAS.

A note on couples: the NRMP Couples Match is a rank-list pairing mechanism that operates at the Match layer, regardless of which application platform each partner uses. It is not a ResidencyCAS feature and does not change how either partner files an application.

You're still in the Match: what ResidencyCAS does NOT change

The most common misconception is that moving to a new application platform means a different Match. It does not. ResidencyCAS is the application, and only the application. Liaison's own quick-start guide says so directly: "Registering with a match service is not a prerequisite for either applying or submitting your ResidencyCAS application," and "Completing your ResidencyCAS application does not register you for any match service." ECFMG adds: "If your specialty participates in the NRMP Match, you will need to register separately with the NRMP."

Emergency Medicine and OB/GYN are NRMP Match specialties. You register with the NRMP separately, exactly as ERAS applicants do; you build a rank list; and you match on NRMP Match Day, March 19, 2027 — the same day, under the same algorithm, as every ERAS specialty. Switching to ResidencyCAS changes where you file your application, not how you match.

Fees, dates, and the August program roster

Fees (2026-27 snapshot — verify on Liaison before you pay). ResidencyCAS fees are charged per specialty, tiered by how many programs you apply to within that specialty:

Special pricing of $10 per program applies to applicants sending 9 or fewer applications overall (such as within a single combined specialty), and a fee waiver covers up to 30 submissions within one specialty for applicants with a prior AMCAS, MCAT, or AACOM waiver. Fees change every cycle — treat this as a dated snapshot, not an evergreen table.

Key dates. The 2026-27 ResidencyCAS calendar mirrors ERAS almost exactly: the cycle opened June 4, 2026; applicants may submit September 2, 2026; programs may access applications September 23, 2026; the cycle closes May 31, 2027. A specialty-specific application deadline (a mid-September date appears in Liaison's quick-start guide) may apply to individual specialties or programs — confirm it against your own program list rather than treating it as a universal ResidencyCAS deadline. For the full planner, use the 2027 residency timeline and key dates.

The August roster. Liaison publishes the full list of participating programs, per specialty, in August, sourced from NRMP participation. Until then, do not rely on a program count or a specific program list for the coming cycle — check the residency rubric hub for our current coverage, and confirm your programs on Liaison's participating-programs page once the roster drops.

FAQ

Which specialties use ResidencyCAS? For 2026-27, exactly two: Emergency Medicine and Obstetrics & Gynecology. Every other specialty uses ERAS.

Does emergency medicine still use ERAS? No. Emergency Medicine moved to ResidencyCAS for the 2025-26 cycle and continues there for 2026-27.

Does OB/GYN use ERAS or ResidencyCAS? ResidencyCAS. OB/GYN was the first specialty to move, in the 2024-25 cycle.

Is ResidencyCAS the same as the Match? No. ResidencyCAS is only the application platform. You register with the NRMP separately, and Match Day is the same for ResidencyCAS and ERAS specialties.

Can I write different personal statements for different programs on ResidencyCAS? No. You submit one statement per specialty, shared with every program in it, with no per-program tailoring. Use Program Signals to express interest in specific programs.

What is the ResidencyCAS personal statement character limit? Reported as roughly 4,000 characters. Liaison confirms a live cap is enforced but does not publish the exact digit in its help text — verify against the live application before you rely on the number.

If you want a professional read before you submit — on either platform — the residency personal statement review works from the same statement, whichever portal your specialty uses.

Sources

• ECFMG — ERAS support for ResidencyCAS (two participating specialties; separate NRMP registration): https://www.ecfmg.org/eras/residencycas.html (accessed 2026-07-26)
• Liaison — ResidencyCAS Applicant Help Center, Personal Statement / Essay (one statement per specialty; no per-program tailoring; live character cap): https://help.liaisonedu.com/ResidencyCAS_Applicant_Help_Center/Filling_Out_Your_ResidencyCAS_Application/Supporting_Information/04_Essay (accessed 2026-07-26)
• Liaison — ResidencyCAS Application Fees (per-specialty fee tiers and waiver): https://help.liaisonedu.com/ResidencyCAS_Applicant_Help_Center/Starting_Your_ResidencyCAS_Application/Getting_Started_with_Your_ResidencyCAS_Application/03_Application_Fees (accessed 2026-07-26)
• Liaison — ResidencyCAS Quick Start Guide (match-service disclaimers; cycle dates): https://help.liaisonedu.com/ResidencyCAS_Applicant_Help_Center/Starting_Your_ResidencyCAS_Application/Getting_Started_with_Your_ResidencyCAS_Application/01_Quick_Start_Guide (accessed 2026-07-26)
• ResidencyCAS — Applicants page (EM and EM-combined tracks, incl. EM/Aerospace Medicine; OB/GYN): https://residencycas.com/applicants/ (accessed 2026-07-26)
• CORD — ResidencyCAS Update from the Board of Directors (EM first cycle completed; ~$780,000 in savings): https://www.cordem.org/news/residencycas-update-from-the-cord-board-of-directors/ (accessed 2026-07-26)
• ACOG — ResidencyCAS (OB/GYN transition to residency; first-year applicant volume): https://www.acog.org/education-and-events/creog/training-and-career-development/transition-to-residency/residencycas (browser-verified 2026-07-20)
• AMA — How emergency medicine's new application could affect your Match (two applications for dual applicants; single-statement intent; ~5% dual-applying): https://www.ama-assn.org/medical-students/preparing-residency/how-emergency-medicine-s-new-application-could-affect-your (accessed 2026-07-26)
• NRMP — Policy Announcement and FAQs: Application Service (the Match is separate from the application service): https://www.nrmp.org/about/news/2023/08/policy-announcement-and-faqs-application-service/ (accessed 2026-07-26)