Purchase Price Allocation Explained: Why Goodwill Is a Residual, How the Asset Write-Up Spawns a Deferred Tax Liability, and the Incremental D&A That Quietly Depresses EPS
Michael King, PE Investment Manager · 9 min read ·
- Goodwill is a residual, not a calculation: it is the purchase price minus the fair value of net identifiable assets — the premium no asset on the balance sheet, even marked to fair value, can account for
- Before any goodwill is struck, the premium is allocated to identifiable assets written up to fair value — property, plant and equipment, and intangibles such as customer relationships, brands and developed technology. Only the unallocated remainder becomes goodwill
- In a share deal the assets’ tax basis does not step up, so the book write-up creates a deferred tax liability of write-up × tax rate — and because that liability reduces identifiable net assets, it increases goodwill pound for pound
- The written-up PP&E and finite-life intangibles carry incremental depreciation and amortisation that depresses post-deal EPS for years. Goodwill itself is never amortised — it sits on the balance sheet until an impairment test writes it down
Goodwill Is the Plug, Not a Number You Calculate
The reflex answer — “goodwill is the premium over book value” — is close enough to sound informed and wrong enough to fail the follow-up. Goodwill is not a line anyone computes directly. It is the amount left over once the price paid has been spread across everything the buyer can actually identify. Accounting standards force a buyer to record the assets acquired and liabilities assumed at fair value, not the target’s book value, and only what refuses to be allocated to an identifiable asset is booked as goodwill.
The formula is therefore a subtraction, not an addition: goodwill = purchase price − fair value of net identifiable assets. Everything interesting happens in that second term, because “net identifiable assets at fair value” is not the balance sheet you inherit — it is that balance sheet after two adjustments most candidates never make.
The Write-Up Comes First: Fair Value Before Residual
Take an acquirer paying £500M for a target whose book value of equity is £200M. The naive answer stops here and calls the £300M premium goodwill. It is not. Before goodwill is struck, the buyer’s advisers run a purchase price allocation and mark the identifiable assets up to fair value: property and equipment carried below replacement cost, and — almost always the larger number — intangibles the target never recognised because it built them rather than bought them.
Customer relationships, order backlog, brand names, patents and developed technology sit at zero or near-zero on a target’s own balance sheet, yet they are a large part of what the buyer is paying for. In the allocation they are recognised at fair value and become identifiable intangibles — distinct from goodwill precisely because they can be named, valued and, where they have a finite life, amortised. Only the premium that no identifiable asset can absorb is left for goodwill.
| Line | Amount | Running residual |
|---|---|---|
| Equity purchase price | £500M | £500M |
| Less: target book value of equity | −£200M | £300M |
| Less: write-up of PP&E to fair value | −£50M | £250M |
| Less: write-up of identifiable intangibles | −£100M | £150M |
| Plus: deferred tax liability on the write-ups (25% × £150M) | +£37.5M | £187.5M |
The £300M premium and the £187.5M of goodwill are not two roughly-similar numbers; they describe two different deals. The gap between them is the write-up — and the write-up carries a tax consequence that pushes goodwill back up again.
Why the Write-Up Spawns a Deferred Tax Liability
Here is the step that separates a rehearsed answer from a memorised one. When the buyer writes an asset up to fair value for accounting, the tax authorities do not follow. In a share deal — the acquirer buys the target’s shares — the assets keep their old, lower tax basis. So the same asset now carries a high book value and an unchanged tax value, and that gap is a taxable temporary difference: a deferred tax liability.
The whole complication exists only because the tax basis did not move. It is the difference between the two deal structures that decides whether it appears at all.
The Incremental D&A That Quietly Depresses EPS
The write-up is not a one-off balance-sheet entry; it reaches into the income statement every year thereafter. The written-up PP&E and the finite-life intangibles must be depreciated and amortised over their useful lives, and that incremental D&A is a new expense the combined company did not carry before the deal. On the £150M written up here — say the £50M of PP&E over ten years and the £100M of intangibles over ten — that is roughly £15M a year of extra pre-tax charge, or about £11M after tax, landing directly on net income.
This is the mechanism behind a large slice of the dilution in any accretion/dilution analysis. The charge is non-cash — no money leaves the business — but reported EPS is an accounting number, and the incremental amortisation is real to it. A deal that looks accretive on cash can print as dilutive on GAAP or IFRS EPS purely because the intangibles the buyer paid for are now amortising through the P&L. It is why acquirers lean so heavily on “cash EPS” and adjusted figures that strip the write-up amortisation back out.
The asymmetry is the point: the identifiable write-ups amortise and drag earnings, while the largest number in the allocation sits on the balance sheet doing nothing to the P&L at all — until, one day, it does.
Goodwill Does Not Amortise; It Waits to Be Impaired
Under IFRS 3 and US GAAP alike, goodwill is not amortised. Since the early 2000s it is instead tested for impairment at least annually: the buyer compares the carrying value of the acquired business against its recoverable amount, and only if the business is worth less than its book value is goodwill written down — a one-off, non-cash charge straight through the income statement. Indefinite-life intangibles, such as certain brands, follow the same impairment-only path; finite-life intangibles amortise.
The consequence is that goodwill is dormant on the P&L until it is not. A quiet balance sheet can carry goodwill for a decade and then take a single brutal impairment when a deal disappoints — the accounting admission, years late, that the premium paid was never recovered. It is the same confession the three-statement mechanics make in miniature: an impairment reduces net income and retained earnings and writes down the asset, and because it is non-cash it is added straight back on the cash flow statement.
The Verdict: Goodwill Is a Residual and a Confession
Purchase price allocation is where the price agreed in the deal room meets the discipline of the accounts, and it resolves into one honest number. Goodwill is what the buyer paid that cannot be pinned to any asset it can name — the value of the workforce, the market position, the expected synergies, and, bluntly, the overpayment. That is why it is a residual and not a calculation: it is defined as whatever is left, and whatever is left is precisely the part of the price the balance sheet cannot justify.
The candidate who says “goodwill is the premium over book value” has the direction right and the machinery missing. The one who says “goodwill is the purchase price less the fair value of net identifiable assets — so you write PP&E and intangibles up first, add back a deferred tax liability of the write-up times the tax rate because a share deal doesn’t step up the tax basis, and remember the write-ups then amortise through EPS while the goodwill just waits to be impaired” is describing the entries a real deal actually books. The premium is the easy number. The allocation is the job.
Take Your Preparation Further
Purchase price allocation sits at the join between accounting and deal execution, so read it alongside both. Ground the three-statement mechanics it relies on in the IB accounting interview questions; see where the incremental D&A lands on EPS in accretion/dilution analysis; and see how the deferred tax and other non-financial claims move the price in the debt-like items bridge. For the wider context of where in the deal the allocation is run, work through the M&A process from mandate to close.
For the full set of purchase-accounting entries on one page — the write-up, the DTL, the goodwill plug and the incremental D&A, with worked model answers — download the free Accounting Cheat Sheet, and to build the allocation yourself inside a live deal model, see the Merger Model Template.
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Frequently asked questions
How is goodwill calculated in an acquisition?
Goodwill is not calculated directly — it is a residual. It equals the purchase price minus the fair value of the net identifiable assets acquired. In practice the buyer first allocates the premium over book value to identifiable assets by writing them up to fair value (property and equipment, and intangibles such as customer relationships, brands and developed technology), then adds back any deferred tax liability created by those write-ups, and whatever premium is still left over becomes goodwill. On a £500M purchase of a target with £200M book equity, £150M of write-ups and a £37.5M deferred tax liability, goodwill is £500M − £312.5M = £187.5M.
Why does writing up an asset create a deferred tax liability?
Because in a share deal the write-up is recognised for accounting but not for tax. When the buyer marks an asset up to fair value, its book value rises while its tax basis stays at the old, lower figure. That gap is a taxable temporary difference: the extra book depreciation and amortisation on the written-up value will not be tax-deductible, so future tax will be higher than the book charge implies. Accounting standards require that future tax to be booked now as a deferred tax liability equal to the write-up times the tax rate — £37.5M on a £150M write-up at 25% — which then unwinds as the write-up is depreciated. In an asset deal the tax basis does step up, so no deferred tax liability arises.
Does the deferred tax liability increase or decrease goodwill?
It increases goodwill. Because goodwill is the residual after the fair value of net identifiable assets, and the deferred tax liability is a liability that reduces those net identifiable assets, adding the DTL leaves more premium unallocated and therefore more goodwill. Without the DTL, goodwill in the worked example would be £150M; the £37.5M DTL pushes it up to £187.5M. It is counter-intuitive — the tax you will eventually pay on an asset you wrote up today is recorded as extra goodwill.
Does goodwill get amortised or depreciated?
No. Under both IFRS 3 and US GAAP, goodwill is not amortised. It is instead tested for impairment at least annually, and written down only if the acquired business is worth less than its carrying value — a one-off, non-cash charge to the income statement. This differs from the identifiable intangibles created in the same allocation: finite-life intangibles such as customer relationships and developed technology are amortised over their useful lives, and that amortisation is the incremental D&A that depresses post-deal EPS. Goodwill itself sits untouched on the balance sheet until an impairment event.
How does the write-up affect EPS in a merger model?
The written-up PP&E and finite-life intangibles carry incremental depreciation and amortisation — roughly £15M a year pre-tax in the worked example — which is a new expense the combined company did not have before the deal. That charge reduces net income and therefore diluted EPS, and is a major driver of dilution in an accretion/dilution analysis. Crucially it is non-cash: it is added back on the cash flow statement and does not touch cash or debt paydown. That is why acquirers emphasise "cash EPS" or adjusted earnings that strip the write-up amortisation back out — a deal can be accretive on a cash basis while printing as dilutive on reported GAAP or IFRS EPS purely because of the intangible amortisation.