"Walk me through purchase accounting" is one of those interview questions that sounds simple until you're actually asked it under pressure. Interviewers use it to check whether you understand fair value accounting, deferred taxes, and goodwill all at once — and most candidates either give a one-sentence definition or get lost trying to remember every line item. Here's a framework that holds up in the room.

Step 1: Start With the One-Sentence Version

Before diving into numbers, anchor the interviewer with the core idea: "When a company is acquired, the acquirer has to restate the target's assets and liabilities to fair value, and whatever it paid above that fair value becomes goodwill." This single sentence signals you know the destination before you start walking through the mechanics.

Step 2: Separate What Changes From What Doesn't

Most candidates try to restate the entire balance sheet, which wastes time and invites mistakes. In reality, only a handful of items typically move to fair value:

  • Property, plant & equipment (often stepped up)
  • New intangible assets that weren't on the target's books at all (customer relationships, technology, trade names)
  • Deferred revenue (almost always written down, not up — the "haircut")

Working capital and most other liabilities are usually assumed to already approximate fair value, which keeps the calculation focused. The deferred revenue haircut in particular is the same concept covered in What Is Deferred Revenue? A Finance Interview Guide, just applied at the moment of an acquisition rather than in the ordinary course of business.

Step 3: Don't Forget the Deferred Tax Liability

This is the step that separates a strong answer from an average one. In a typical stock deal, stepping up assets for book purposes without a matching step-up in tax basis creates a new deferred tax liability, equal to the total step-up multiplied by the tax rate. Skipping this understates total liabilities — and therefore understates goodwill.

Step 4: Solve for Goodwill as the Plug

Once you have the fair value of net identifiable assets (all restated assets minus all restated liabilities, including the new DTL), goodwill is simply:

Goodwill = Purchase Price − Fair Value of Net Identifiable Assets Acquired

Say it exactly like that — as a plug, not as something you calculate directly. Interviewers listen for that framing specifically.

Step 5: Mention the Forward-Looking Consequences

A complete answer doesn't stop at the balance sheet on day one. Two things follow the deal going forward: the stepped-up PP&E and new intangibles generate incremental depreciation and amortization that lowers pro forma net income, and the deferred revenue haircut means the combined company will report less revenue in the near term than the target would have standalone — a purely accounting effect, not a business one.

See the Full Numbers Worked Through

Reading the framework is one thing; working the actual numbers is what makes it stick. Our case Purchase Accounting After an Acquisition runs through this exact five-step process on a $500m deal — deferred tax liability, goodwill, incremental D&A, and the deferred revenue haircut — with every formula and number shown. If you want to go one step further into what happens when the deal doesn't perform, pair it with Goodwill: Creation and Impairment, which covers the impairment test that goodwill faces every year after close.

The Conceptual "Why" Behind This Framework

This five-step framework is the "how do I answer it" companion to a deeper conceptual question: why does accounting insist on restating everything to fair value in the first place, rather than simply combining the two companies' book values? What Is Purchase Accounting? Goodwill, Step-Ups, and the Deferred Revenue Haircut Explained unpacks that underlying logic in more depth, including why the deferred revenue haircut specifically trips up even experienced analysts — useful background if the interviewer pushes past the mechanical five-step answer into "why does this rule exist at all."

A Numerical Variation to Practice

To make sure the underlying logic is understood rather than memorized from a single $500m deal, run through a $150m acquisition where PP&E is stepped up by $12m and a new $8m technology intangible is recorded, at a 25% tax rate. Step 1: state the one-sentence version — restate to fair value, goodwill absorbs the excess. Step 2: identify the moving pieces — PP&E, the new intangible, and a deferred revenue haircut on the target's $5m balance down to $2m. Step 3: the deferred tax liability is 25% of the combined $20m step-up ($12m + $8m), or $5m. Step 4: if fair-valued net identifiable assets come to $115m, goodwill is $150m − $115m = $35m. Step 5: the combined company will carry incremental D&A from the $20m of step-ups going forward, and will report $3m less revenue in the near term from the deferred revenue haircut. Running the same five-step framework against a different deal size, rather than only reciting the original numbers, is what separates a candidate who understands the mechanic from one who has memorized a single case's arithmetic.

Common Ways Candidates Lose Points on This Question

A few recurring mistakes show up when candidates answer this prompt under interview pressure. Some skip the deferred tax liability step entirely, understating goodwill without realizing it. Others describe goodwill as if it were independently calculated rather than a plug, which signals to the interviewer that the mechanic isn't fully understood. Still others forget Step 5 entirely, stopping at the balance sheet on day one without mentioning the incremental D&A or the deferred revenue haircut's effect on near-term reported revenue. Avoiding these three slips is what separates a clean answer from a shaky one.

How This Question Escalates at the Associate Level

At the analyst level, interviewers are typically satisfied once a candidate correctly runs through the five-step framework and lands on the right goodwill figure. At the associate level, the question often extends into modeling and deal-structuring judgment — for instance, asking how the choice between a stock deal and an asset deal affects whether the target gets a stepped-up tax basis, or asking a candidate to walk through how the incremental D&A and deferred revenue haircut flow into an accretion/dilution analysis for the first full year post-close. Being ready to move from "here is the mechanical five-step answer" to "here is how this affects deal structuring and modeling" is what separates a strong associate-level answer from a merely correct analyst-level one.

A Pre-Interview Checklist for This Question

Before an interview where this exact framing might come up, it's worth confirming: can you state the one-sentence version of purchase accounting from memory; can you name the three items that typically move to fair value; can you explain why the deferred tax liability arises and how it's calculated; can you state the goodwill formula as a plug, not a direct calculation; and can you proactively mention the incremental D&A and deferred revenue haircut as forward-looking consequences. If any of these feel shaky, revisit the full worked case and the companion conceptual article linked above before attempting this question again.

Why This Framework Works for Any Deal Size

The five-step order in this article isn't specific to $500m deals — it's a general-purpose template for any acquisition, because every deal requires the same underlying questions: what moves to fair value, what tax liability results, what's left over as goodwill, and what happens to earnings and revenue afterward. A candidate who has internalized this structure can handle a $50m deal or a $50bn deal with equal confidence, while a candidate who has only memorized one case's specific numbers will struggle the moment the interviewer changes the deal size or asset mix.

Why This Question Is a Favorite Screening Tool

Interviewers return to this exact question because it's one of the few that simultaneously tests accounting fundamentals, tax mechanics, and modeling judgment in a single prompt. Because purchase accounting sits at the intersection of accounting, tax, and M&A analysis — three areas that show up constantly in interviews for deal-focused roles — mastering the five-step framework here pays off well beyond this specific question, and prepares a candidate for the inevitable follow-ups about deal structuring, accretion/dilution, and post-close goodwill impairment testing. If those follow-ups arise, Why Doesn't a Goodwill Impairment Increase Cash Flow? The Missing Tax Shield Explained is the natural next article to work through.

Industry Patterns Worth Knowing Before the Interview

How large each step of this framework turns out to be depends heavily on the industry involved. Software and services acquisitions tend to generate large deferred revenue haircuts and a high proportion of purchase price allocated to goodwill and intangibles, since so much of the target's value sits in customer relationships and technology rather than physical assets. Industrial and manufacturing acquisitions, by contrast, typically involve larger PP&E step-ups relative to goodwill, since more of the target's value sits in tangible, separately identifiable assets. Knowing which industries push weight toward which steps of the framework demonstrates a more grounded understanding of the topic than treating every deal identically.

How This Connects to Depreciation Mechanics You Already Know

The PP&E step-up in Step 2 isn't a new concept — it's the same capitalize-and-depreciate mechanic tested in 3-Statement Change: Depreciation Increases by $100, just applied to a revalued asset base at the moment of an acquisition rather than a newly purchased asset. Recognizing that connection makes Step 5's mention of incremental D&A feel like a natural extension of a mechanic you already know, rather than a new one to memorize separately.

The Takeaway

The five-step order in this article — anchor with the one-sentence version, identify what moves to fair value, calculate the deferred tax liability, solve for goodwill as the plug, and mention the forward-looking consequences — is a template, not a script tied to this one $500m example. Practicing it against a handful of different deal sizes and asset mixes, rather than memorizing the original numbers verbatim, is what makes a candidate resilient to however the interviewer happens to phrase the question, and it's the foundation for handling every follow-up about what happens to that goodwill in the years after the deal closes.