Understanding Depreciation Methods

Depreciation is the systematic allocation of an asset's cost over its useful life. It reduces the asset's book value over time to reflect its declining economic value as it ages, wears out, or becomes obsolete. Depreciation is required by accounting standards (GAAP and IFRS) for all tangible fixed assets with a limited useful life.

AccuArk supports five depreciation methods. This guide explains each one in detail with formulas, worked examples, and guidance on when to use each method.

Key Terms

Before diving into the methods, make sure you understand these foundational terms:

The fundamental formula is:

Depreciable Base = Total Capitalized Cost - Salvage Value

Method 1: Straight-Line (SL)

Straight-line is the simplest and most commonly used depreciation method. It spreads the depreciable base evenly across every month of the asset's useful life.

Formula

Monthly Depreciation = Depreciable Base / Useful Life in Months

Example

Consider a delivery van with the following values:

• Total Capitalized Cost: $12,000
• Salvage Value: $2,000
• Useful Life: 60 months (5 years)

Calculation:

• Depreciable Base = $12,000 - $2,000 = $10,000
• Monthly Depreciation = $10,000 / 60 = $166.67

Every month for 60 months, $166.67 of depreciation expense is recorded. After 60 months, the asset's book value equals its $2,000 salvage value.

When to Use

Straight-line is best for assets that provide consistent, even value over their entire life. Common examples include:

• Office furniture
• Buildings and leasehold improvements
• General-purpose equipment
• Fixtures and fittings

This is the most commonly used method and is appropriate for the majority of assets in most businesses.

Method 2: Declining Balance (DB)

Declining balance is an accelerated method that depreciates a fixed percentage of the asset's remaining book value each period. This results in higher depreciation in the early years and progressively lower amounts as the asset ages.

Formula

Annual Rate = 1 / Useful Life in Years

Monthly Depreciation = Current Book Value x Annual Rate / 12

Note that the rate is applied to the current book value (not the original cost), which is why the depreciation amount decreases each period.

Example

Using the same $12,000 van with a 5-year life:

• Annual Rate = 1 / 5 = 20%
• Year 1: $12,000 x 20% = $2,400 annual ($200/month)
• Year 2: $9,600 x 20% = $1,920 annual ($160/month)
• Year 3: $7,680 x 20% = $1,536 annual ($128/month)
• And so on, with each year's depreciation being smaller

The process continues until the book value reaches the salvage value, at which point depreciation stops.

When to Use

Declining balance is appropriate for assets that lose value more quickly in their early years. This method produces a moderate acceleration of depreciation compared to straight-line.

Method 3: Double Declining Balance (DDB)

Double declining balance works the same way as declining balance but uses twice the straight-line rate, making it significantly more front-loaded.

Formula

Annual Rate = 2 / Useful Life in Years

Monthly Depreciation = Current Book Value x Annual Rate / 12

Example

Using the same $12,000 van with a 5-year life:

• Annual Rate = 2 / 5 = 40%
• Year 1: $12,000 x 40% = $4,800
• Year 2: ($12,000 - $4,800) x 40% = $7,200 x 40% = $2,880
• Year 3: ($7,200 - $2,880) x 40% = $4,320 x 40% = $1,728
• Year 4: ($4,320 - $1,728) x 40% = $2,592 x 40% = $1,036.80

Automatic Crossover to Straight-Line

AccuArk automatically switches from DDB to straight-line when the straight-line method would produce a larger deduction for the remaining useful life. This is the optimal crossover point and ensures that the full depreciable base is consumed by the end of the useful life.

Without this crossover, a pure DDB method would never fully depreciate the asset to its salvage value because you are always taking a percentage of a shrinking number.

When to Use

DDB is best for assets that lose value very rapidly in their first few years:

• Technology equipment (computers, servers, networking gear)
• Vehicles (cars, trucks, delivery vans)
• Electronics and mobile devices
• Software licenses with declining utility

Method 4: Sum-of-Years-Digits (SYD)

Sum-of-years-digits is another accelerated method. It applies a fraction to the depreciable base each year, where the fraction decreases as the asset ages.

Formula

First, calculate the sum of the years digits. For a 5-year life:

Sum of Years = 5 + 4 + 3 + 2 + 1 = 15

Or using the formula: Sum = n x (n + 1) / 2 where n is the useful life in years.

Then for each year:

Annual Depreciation = Depreciable Base x (Remaining Life in Years / Sum of Years)

Example

Using the same $12,000 van, $2,000 salvage, 5-year life:

• Depreciable Base = $10,000
• Sum of Years = 15
• Year 1: $10,000 x 5/15 = $3,333.33
• Year 2: $10,000 x 4/15 = $2,666.67
• Year 3: $10,000 x 3/15 = $2,000.00
• Year 4: $10,000 x 2/15 = $1,333.33
• Year 5: $10,000 x 1/15 = $666.67
• Total: $10,000 (exactly equals the depreciable base)

Notice that unlike declining balance methods, SYD always depreciates exactly the full depreciable base over the useful life without needing a crossover.

When to Use

SYD provides acceleration that is less aggressive than DDB but more than straight-line. It is a good choice for:

• Equipment with clearly declining productivity over time
• Assets that require increasing maintenance costs as they age (accelerated depreciation offsets the rising repair costs)
• Situations where you want moderate front-loading without the complexity of declining balance

Method 5: Units of Production (UOP)

Units of production ties depreciation directly to the asset's actual usage rather than time. The more the asset is used in a period, the more depreciation is recorded.

Formula

Rate per Unit = Depreciable Base / Total Estimated Units

Period Depreciation = Rate per Unit x Units Produced This Period

Example

Consider a CNC milling machine:

• Total Capitalized Cost: $50,000
• Salvage Value: $5,000
• Total Estimated Operating Hours: 100,000

Calculation:

• Depreciable Base = $50,000 - $5,000 = $45,000
• Rate per Hour = $45,000 / 100,000 = $0.45
• If the machine runs 2,000 hours this month: $0.45 x 2,000 = $900 depreciation
• If the machine runs only 500 hours next month: $0.45 x 500 = $225 depreciation

The depreciation amount varies each period based on actual usage.

Meter Readings Required

Units of production requires that you maintain current meter readings for the asset. The meter reading tracks the cumulative units produced (hours run, miles driven, cycles completed, etc.). You must update the meter reading before each depreciation run so the system can calculate the period's usage.

When to Use

UOP is ideal when an asset's wear is directly related to usage:

• Manufacturing equipment (measured by operating hours or units produced)
• Vehicles (measured by miles or kilometers driven)
• Printing equipment (measured by print cycles or impressions)
• Mining equipment (measured by tons extracted)

This method produces the most accurate matching of depreciation expense to actual asset consumption.

Salvage Value Floor

Regardless of which depreciation method you use, AccuArk enforces a salvage value floor. No method will depreciate an asset below its salvage value. Once the asset's book value equals the salvage value, depreciation stops automatically and the asset is flagged as fully depreciated.

A fully depreciated asset remains on your books at its salvage value until it is disposed of. It does not appear in future depreciation runs.

Pro-Rating for Mid-Period Acquisitions

Assets acquired in the middle of a period are pro-rated for partial-period depreciation. If an asset is purchased on the 15th of a 30-day month, AccuArk calculates only half a month's depreciation for that first period.

This ensures that the first depreciation run accurately reflects the actual time the asset was in service during the period, rather than charging a full period's depreciation for an asset that was only owned for part of it.

Changing Depreciation Methods

You can change the depreciation method on an existing asset at any time. When you do:

• The change takes effect for future depreciation calculations only
• Previous depreciation entries are not recalculated or reversed
• The system uses the asset's current book value as the starting point for the new method
• The remaining useful life is used for the new calculation

For example, if you switch from DDB to straight-line midway through an asset's life, the remaining depreciable base (current book value minus salvage value) is spread evenly over the remaining useful life months.

Choosing the Right Method

Here is a summary to help you decide which method to use:

When in doubt, straight-line is almost always a safe and defensible choice.

Related Articles

• Running Depreciation
• Logging Maintenance Events
• Asset Acquisition Wizard