What are deferred taxes and NOLs, and why do they matter in deals?

Q: What is a deferred tax liability and what commonly creates one?

A DTL represents taxes owed but not yet paid, arising when book income exceeds taxable income. The most common driver is accelerated depreciation: companies use straight-line for GAAP but MACRS for tax, paying less tax now but owing it later. DTLs are sometimes treated as quasi-equity in valuation because they may perpetually roll forward.

Q: How do net operating losses create a deferred tax asset?

When tax deductions exceed taxable revenue, the resulting loss creates an NOL that can offset future taxable income. The DTA equals the NOL carryforward balance times the tax rate. Post-2017 TCJA rules allow indefinite carryforward but limit annual usage to 80% of taxable income. NOL carrybacks were eliminated except for a brief 2018-2020 window.

Q: What is Section 382 and why does it matter in M&A?

Section 382 limits annual NOL usage after ownership changes. If more than 50% of stock changes hands within three years, annual NOL usage is capped at equity value times the long-term tax-exempt rate (roughly 5%). This can destroy NOL value overnight, making it a critical due diligence item in acquisitions of loss-making companies.

Q: What is a valuation allowance on deferred tax assets?

A valuation allowance is a contra-asset that reduces DTAs when it's more likely than not (over 50% probability) that the DTA won't be realized. A startup with $500M in NOLs but no path to profitability would have its entire DTA offset. Releasing a valuation allowance boosts reported earnings without any cash changing hands, so watch for manipulation.

Q: Why does a purchase price allocation create a deferred tax liability?

In a stock acquisition, the buyer writes assets up to fair value for book purposes while the tax basis carries over unchanged. The extra book depreciation from the write-up is never tax-deductible, so future taxable income will exceed book income. The DTL equals the step-up times the tax rate, and recording it increases goodwill by the same amount. In an asset deal the tax basis steps up too, so no DTL arises.

Master deferred tax assets, liabilities, and NOL carryforwards for IB interviews. Covers book-tax timing differences and valuation allowances.

Accelerated

OFFERGOBLIN·8 min read·updated August 2026

On this page

Concept
Intuition
Components
Core framework
Deferred tax liabilities (DTLs)
DTLs created in a purchase price allocation
Deferred tax assets (DTAs)
Net operating losses (NOLs)
Valuation allowance
Interview script

"The only difference between death and taxes is that death doesn't get worse every time Congress meets." (Will Rogers)

Concept

Deferred taxes arise when a company's book income (reported to shareholders under GAAP) differs from its taxable income (reported to the IRS). These timing differences create either Deferred Tax Assets (future tax savings) or Deferred Tax Liabilities (future tax payments). Net Operating Losses (NOLs) are a specific type of DTA: accumulated losses that can offset future taxable income.

Intuition

The IRS and GAAP serve different masters. GAAP wants to match revenues and expenses in the period they economically occur. The IRS wants cash. It lets you accelerate deductions to incentivize investment. This creates timing mismatches that must eventually reverse.

DTLs are essentially interest-free loans from the government.
DTAs are prepaid tax credits, but only if you live long enough to use them.
NOLs are the extreme case: losses so large they carry forward for years, reducing future tax bills. But they're fragile: change ownership and Section 382 can wipe out their value overnight.

Frequently Asked Questions

What is a deferred tax liability and what commonly creates one?

How do net operating losses create a deferred tax asset?

What is Section 382 and why does it matter in M&A?

What is a valuation allowance on deferred tax assets?

Why does a purchase price allocation create a deferred tax liability?