EY-Parthenon Case Interview: Process, Format and Practice

An EY-Parthenon case interview is a live business problem you solve with an EY-Parthenon consultant or partner, usually alongside behavioral or CV questions, and EY-Parthenon's Australian page says the case tests how you think rather than what you already know. The process varies by country: the US page promises "a mix of behavioral and case-based interviews," while the Dutch, German and Australian pages spell out different rounds, tests and interview counts. Here's the process described on those pages and a fictional due diligence case you can solve out loud.

Soreno isn't affiliated with EY or EY-Parthenon. Every process detail here comes from EY's own careers and service pages, read on October 1, 2026, and we name the country each one applies to.

What EY says about the EY-Parthenon process, by country

Each country runs its own EY-Parthenon hiring. The US Associate Program page says so: "Hiring processes, needs and timelines will vary by country and are managed by the respective country." Here's what the pages we read say:

A US page covering all EY early-careers hiring adds more. The application guidance page says you'll get an email "within one business day" to complete an EY skills assessment, and that "The style, format and number of rounds of EY interviews are based on business needs and may include prerecorded video, live video and case study interviews."

EY's UK students page covers general early-careers opportunities. EY UK's general application process page describes online assessments and an EY Experience Day, but doesn't say how EY-Parthenon's UK interviews work.

What EY doesn't publish

Prep sites give exact formats for EY-Parthenon. The EY pages we read leave out a lot:

• The US pages give no number of rounds, no interview length and no case format.
• No EY page we read says whether cases are candidate-led or interviewer-led, though prep sites often call them candidate-led.
• Only the Dutch page names a numerical test. The US "EY skills assessment" isn't described.
• None of the EY-Parthenon pages we read describe a written case, a group case or a presentation.
• Case length isn't given anywhere, except that Germany's one-hour virtual interview includes one.

Your recruiter's email is the source that counts, so ask about format and length if the invite doesn't say.

What the case is testing, in EY's words

The Australian page is the most detailed. It describes cases based on real business scenarios, worked through using qualitative reasoning and calculations. Its central point: "These problems assess how you think and approach a problem, rather than what you know." It advises you to avoid scripts and stock frameworks. Focus on communicating and structuring your thinking clearly. It also tells you to ask questions when something's unclear rather than rush to force a solution.

The same page has a sample case on whether a client should invest in a new electricity plant, run as five questions in sequence. You list the analyses you'd want, estimate national electricity use from a few hints, interpret a capacity and demand fact, and then judge whether to invest when the project only just breaks even. It's the closest thing to an official EY-Parthenon practice case we found, so do it.

The kind of work matters too. EY's due diligence services page says EY-Parthenon's commercial due diligence looks at a target's market, customers, competitive positioning, growth potential and risks, including "Intrinsic attractiveness of the underlying market and target company." EY doesn't say its interview cases come from due diligence work, but the core questions (is this market as big as the seller says, and can the company grow its share?) are good practice. Our merger and acquisition case study covers the deal side more broadly.

Worked example: checking a management market size

This is our own practice case, written in a commercial due diligence style. The company, the fund and every number are made up.

Prompt. A private equity fund is thinking about buying Keystone Inspect, which does fire sprinkler and alarm inspections for commercial buildings in one region. Management's deck says the regional inspection market is worth $600 million, growing 8% a year, and that Keystone will grow revenue from $54 million today to $90 million in five years. The fund asks you whether the market and the plan hold up.

Clarify first. Ask what "inspection" covers (routine inspections, not repairs) and whether Keystone's $54 million is all inspection revenue (yes).

Structure. Say it out loud: "I'd size the market bottom-up, compare it with management's figure, then check what share Keystone needs to hit $90 million." Market size is buildings times inspections per year times price, split by building size because big buildings get inspected more often.

Exhibit (what the interviewer gives you when you ask):

Math, as you'd say it:

• Small: 80,000 inspections × $900 is $72M. Medium: 60,000 inspections × $2,500 is $150M. Large: 40,000 inspections × $6,000 is $240M. Total: $462M.
• Management's $600M is $138M higher, about 30% above our number. When you ask why, the interviewer says management's figure includes repair and upgrade work, which Keystone doesn't sell.
• Keystone's share is $54M / $462M, about 11.7%, not the 9% you'd get from $54M / $600M.

Growth. The interviewer says the number of buildings grows about 1% a year and inspection prices about 3%. So the market grows 1.01 × 1.03 = 1.0403, about 4% a year, half of management's 8%.

Test the plan. Grow the market five years at 4%: $462M × 1.0403 to the fifth power (about 1.218) is about $563M. Keystone's $90M target would be 90 / 563, about 16.0% of that market, up from 11.7%. That's 4.3 share points, or roughly 37% more share than it has today. On management's numbers, the market would be $600M × 1.08 to the fifth (about 1.469), or $882M, and $90M would be only 10.2% share, up from 9%. The plan looks easy only because the market is inflated.

If Keystone just holds 11.7% share, year-five revenue is $54M × 1.218, about $66M. That's $24M short of the plan.

Where share could come from. Ask for Keystone's revenue by segment: $6M small, $18M medium, $30M large. Shares are 8.3% in small buildings ($6M / $72M), 12% in medium ($18M / $150M) and 12.5% in large ($30M / $240M). Large buildings are the biggest pool and Keystone's strongest segment, so a share gain story starts there.

The 30-second recommendation:

"The inspection market is about $460 million and growing around 4% a year, not $600 million at 8%. Management's number includes repair work Keystone doesn't do. On the real market, Keystone has about 12% share, and the $90 million plan needs that to reach 16%. I'd tell the fund to price the deal on a base case of about $66 million in year five, which assumes Keystone holds share, and treat the plan as upside. Before signing, I'd check Keystone's win rate and contract renewals with large-building customers, because that segment has the largest revenue pool. I'd also test whether the smaller segments offer easier wins."

It leads with the corrected number and gives the fund a figure to underwrite.

A 10-minute drill: test a management number

This drill practices checking a management claim against simple math. These four fictional claims take about two minutes each. Answer out loud, then check.

For more sizing practice, our market sizing interview questions have worked answers.

The behavioral side

Every EY-Parthenon page we read pairs the case with questions about you, from Australia's "traditional" interview on your motivation for consulting to Germany's CV discussion.

EY's US interview tips page, which covers all of EY, says it relies on behavioral interviewing, with questions asking for an example or a past situation It judges answers on whether you gave a relevant experience, explained your action and described the result, and suggests preparing 10 to 15 adaptable examples. EY's US interview tips PDF, again covering all of EY, says interviews are typically on video and usually last 30 to 45 minutes, and describes a case study interview as a business scenario you "read through and then discuss" with the interviewer. Neither is specific to EY-Parthenon, so treat them as a general guide. Our behavioral interview questions for consulting has example answers.

Practice cases out loud, because every format above has you explaining your thinking to a person. Soreno's consulting track runs voice AI mock case interviews where you pick interviewer-led or candidate-led format before you start, so you can rehearse both. The AI interviewer shows exhibits live, asks follow-ups and pushes back, and you get a rubric-graded report that scores structure, numeracy and communication among other things. There are also timed drills for market sizing and consulting math. It has no EY-Parthenon case library and doesn't simulate numerical tests or written cases.