Why Depreciation Matters in Investment Banking
Depreciation and amortization are among the most frequently tested accounting topics in investment banking interviews. At first glance, depreciation seems simple -- you are just spreading the cost of an asset over its useful life. But the method you choose affects the income statement, balance sheet, and cash flow statement in ways that ripple through valuation models, tax calculations, and credit analyses.
Understanding depreciation is also essential for grasping the broader concept of capitalization vs. expensing. When a company capitalizes an expenditure, it records the cost as an asset on the balance sheet and then depreciates it over time. When it expenses the cost immediately, the full amount hits the income statement in the current period. This distinction drives some of the most common interview questions in accounting.
This guide covers every depreciation method you need to know, how each affects the financial statements, and why interviewers care.
Straight-Line Depreciation
Straight-line is the simplest and most commonly used depreciation method for financial reporting purposes (GAAP/IFRS books). It allocates the cost of an asset evenly over its useful life.
Formula
Annual Depreciation = (Cost - Salvage Value) / Useful Life
Example: A company purchases a machine for $500,000, with a salvage value of $50,000 and a useful life of 10 years.
Annual Depreciation = ($500,000 - $50,000) / 10 = $45,000 per year
The company records $45,000 of depreciation expense each year for 10 years. At the end of year 10, the asset's book value equals the $50,000 salvage value.
When It Is Used
Straight-line depreciation is the default for most companies in their GAAP financial statements. It is simple, predictable, and easy to audit. Most publicly traded companies use straight-line for external reporting, even if they use an accelerated method for tax purposes.
Interview Context
If an interviewer asks you to "depreciate an asset" without specifying a method, assume straight-line unless told otherwise. It is also the easiest method to build into a financial model because the annual expense is constant.
Double-Declining Balance (DDB)
Double-declining balance is an accelerated depreciation method that front-loads depreciation expense into the earlier years of an asset's life. The logic is that many assets (vehicles, equipment, technology) lose more value in their early years.
Formula
Annual Depreciation = 2 x (1 / Useful Life) x Book Value at Beginning of Year
Note that DDB uses book value, not original cost minus salvage. The "2x" is what makes it "double" -- you are applying twice the straight-line rate.
Example: Same $500,000 machine, 10-year useful life, $50,000 salvage value.
Straight-line rate = 1/10 = 10%. DDB rate = 20%.
| Year | Beginning Book Value | Depreciation (20% x BV) | Ending Book Value | |------|---------------------|--------------------------|-------------------| | 1 | $500,000 | $100,000 | $400,000 | | 2 | $400,000 | $80,000 | $320,000 | | 3 | $320,000 | $64,000 | $256,000 | | 4 | $256,000 | $51,200 | $204,800 | | 5 | $204,800 | $40,960 | $163,840 |
Notice that depreciation expense decreases each year as the book value shrinks. You continue applying the DDB rate until the book value reaches the salvage value -- at that point, you stop depreciating. In practice, companies often switch from DDB to straight-line partway through the asset's life to ensure the asset is fully depreciated by the end of its useful life.
When It Is Used
DDB is less common in financial reporting but appears in interview questions and academic exercises. Some companies use it for assets that truly lose value quickly (technology equipment, for instance). The key takeaway for interviews is understanding how accelerated depreciation shifts expenses earlier.
MACRS (Modified Accelerated Cost Recovery System)
MACRS is the depreciation system required for U.S. federal tax purposes. It is not used in GAAP financial statements, but it is critically important because it determines the actual tax depreciation deduction and therefore affects cash taxes paid.
How MACRS Works
MACRS assigns each asset to a property class with a specified recovery period. The IRS publishes depreciation tables that tell you exactly what percentage of the asset's cost to deduct each year. There is no salvage value under MACRS -- assets are depreciated to zero.
Common MACRS property classes:
- 3-year: Certain manufacturing tools, research equipment
- 5-year: Computers, office equipment, vehicles, certain machinery
- 7-year: Office furniture, most general-purpose machinery
- 15-year: Land improvements, certain utility infrastructure
- 27.5-year: Residential rental property (straight-line under MACRS)
- 39-year: Commercial real estate (straight-line under MACRS)
MACRS Depreciation Table (5-Year Property, 200% Declining Balance)
| Year | Depreciation % | |------|---------------| | 1 | 20.00% | | 2 | 32.00% | | 3 | 19.20% | | 4 | 11.52% | | 5 | 11.52% | | 6 | 5.76% |
Note that a "5-year" property takes 6 calendar years to fully depreciate because MACRS applies a half-year convention -- the IRS assumes you place the asset in service at the midpoint of the first year.
Why MACRS Matters for IB
The difference between book depreciation (straight-line for GAAP) and tax depreciation (MACRS) creates a deferred tax liability on the balance sheet. In the early years, MACRS depreciation exceeds straight-line depreciation, so taxable income is lower than book income. This means the company pays less in cash taxes now but will pay more later when MACRS depreciation declines below straight-line.
This book-tax difference is a common interview topic. If an interviewer asks "what creates a deferred tax liability?", accelerated tax depreciation is one of the most important answers.
Units of Production
The units of production method ties depreciation to the actual usage of an asset rather than the passage of time. It is most appropriate for assets whose wear is driven by output rather than age.
Formula
Depreciation Per Unit = (Cost - Salvage Value) / Total Estimated Units of Production
Annual Depreciation = Depreciation Per Unit x Units Produced in the Year
Example: A printing press costs $1,000,000, has a $100,000 salvage value, and is expected to produce 9,000,000 pages over its life.
Depreciation Per Unit = ($1,000,000 - $100,000) / 9,000,000 = $0.10 per page
If the press produces 1,500,000 pages in Year 1: Depreciation = 1,500,000 x $0.10 = $150,000
When It Is Used
Units of production is common in mining, oil and gas, and heavy manufacturing. In the oil and gas industry, a variant called depletion uses a similar concept to depreciate the cost of natural resource reserves based on extraction volumes.
Interview Context
Units of production rarely appears in standard IB interviews, but it shows up in energy and mining coverage group interviews. If you are interviewing for a natural resources group, understand how depletion works as an extension of this method.
Impact on the Financial Statements
Understanding how depreciation flows through all three statements is essential. Here is the chain of effects:
Income Statement
Depreciation expense reduces operating income (EBIT) and therefore net income. Higher depreciation in a given year means lower reported earnings. The depreciation method directly affects the timing of when this expense is recognized.
Balance Sheet
Depreciation reduces the net book value of PP&E (Property, Plant & Equipment) through accumulated depreciation. On the liabilities side, if the company uses different methods for book and tax purposes, the difference creates deferred tax assets or liabilities.
- Accelerated depreciation for tax > Straight-line for book: Creates a deferred tax liability (you owe taxes later)
- Straight-line for tax > Accelerated for book: Creates a deferred tax asset (you have prepaid taxes)
Cash Flow Statement
Here is the critical insight: depreciation is a non-cash expense. It reduces net income, but no cash actually leaves the business. On the cash flow statement, depreciation is added back to net income in the cash flow from operations section.
However, depreciation does affect cash flow indirectly through taxes. Higher depreciation lowers taxable income, which lowers cash taxes paid. This is the tax shield benefit of depreciation, and it is a core concept in valuation models and LBO analysis.
The classic interview question: "If depreciation increases by $10, what happens to each financial statement?"
- Income statement: Operating income falls by $10, net income falls by $10 x (1 - tax rate) -- let us say $7 at a 30% tax rate
- Cash flow statement: Start with net income (down $7), add back depreciation (up $10), net cash flow increases by $3. This $3 is the tax shield.
- Balance sheet: PP&E decreases by $10 (more accumulated depreciation). Cash increases by $3 (from the tax shield). Retained earnings decreases by $7 (lower net income). The balance sheet balances: assets change by -$10 + $3 = -$7, and equity changes by -$7.
Comparing Depreciation Methods
| Method | Pattern | Salvage Value | Common Use | |--------|---------|---------------|------------| | Straight-Line | Equal expense each year | Yes | GAAP financial reporting | | DDB | Front-loaded, declining | Yes (floor) | Academic exercises, some GAAP | | MACRS | Front-loaded (IRS tables) | No (depreciate to $0) | U.S. tax returns | | Units of Production | Variable (usage-based) | Yes | Mining, oil & gas, manufacturing |
Master Depreciation for Your Interviews
Depreciation questions appear in nearly every IB interview. The interviewers are not testing whether you can recite a formula -- they want to see that you understand the economic logic and can trace the effects through all three financial statements.
Practice with our flashcard system to drill depreciation and amortization concepts, the income statement impact, and the cash flow statement add-back until you can walk through the three-statement impact in your sleep.
Practice what you just learned
Reinforce these concepts with free interactive tools built for IB interview prep.