A Plain English Guide to the Straight Line Depreciation Method

As a business owner, you know that the assets you buy for your company won‘t last forever. Equipment breaks down, vehicles wear out, and buildings eventually need repairs. While the upfront cost of these assets hits your bank account all at once, you don‘t have to expense them all in one year. Instead, you can write off the cost a little bit at a time over the life of the asset using depreciation.

Depreciation is an accounting method that spreads out an asset‘s cost over the years it will be used, matching the expense of the asset to the revenue it generates. There are several depreciation methods, but the most straightforward is the straight line method.

In this guide, we‘ll dive deep into straight line depreciation and how you can use it to accurately expense your business assets over time. We‘ll explain the formula step-by-step with examples, discuss the assumptions and limitations of the method, and show how depreciation impacts your financial statements.

By the end, you‘ll have a clear understanding of how to calculate and record straight line depreciation for your business assets. Let‘s get started!

What is Depreciation?

Before we jump into the specifics of straight line depreciation, let‘s take a step back and look at what depreciation is and why it matters for your business.

In accounting, depreciation is a method for allocating the cost of a tangible asset over its useful life. Rather than expensing the entire cost in the year the asset is purchased, depreciation allows you to spread out the expense over several years.

The purpose of depreciation is to match the cost of an asset to the revenue it helps generate. For example, if you buy a $50,000 machine that will increase your production and revenue for 10 years, it doesn‘t make sense to expense the entire $50,000 in the first year. That would inflate your expenses and make it look like your business was less profitable than it really is.

Depreciation solves this problem by letting you write off a portion of the asset‘s cost each year over its useful life. This way, the expense is matched to the additional revenue the asset helps bring in.

There are a few key reasons why depreciation is so important:

1. It provides a more accurate picture of your business‘s profitability by properly matching expenses to revenue.

2. It helps you make better decisions about when to buy new assets by showing the true cost of using an asset over time.

3. It can lower your tax bill by letting you take a depreciation expense deduction each year.

In fact, depreciation is one of the biggest deductions claimed by businesses on their tax returns. According to the IRS, companies claimed over $1 trillion in depreciation deductions in 2019 alone.

Now that we‘ve covered the basics of depreciation, let‘s take a closer look at the most common depreciation method: straight line depreciation.

The Straight Line Depreciation Method

The straight line depreciation method is the simplest way to calculate depreciation for your business assets. Under this method, you expense an equal amount of depreciation each year over the useful life of an asset.

The main assumption of the straight line method is that the asset‘s economic usefulness and maintenance cost will be roughly the same each year. This makes it a good fit for assets that don‘t lose value quickly or require increasing amounts of repair as they age.

Some examples of assets that are commonly depreciated using the straight line method are:

• Buildings
• Office furniture
• Machinery and equipment
• Vehicles
• Computers and office equipment

Of course, the useful life will vary for each type of asset. A building might have a useful life of 30 years, while a computer may only last 5 years before it needs to be replaced due to wear and tear or obsolescence.

To calculate straight line depreciation, you need to know three key pieces of information about the asset:

1. The initial cost of the asset
2. The asset‘s salvage value (how much it will be worth at the end of its useful life)
3. The asset‘s estimated useful life (in years)

Here‘s the formula for straight line depreciation:

Annual Depreciation Expense = (Asset Cost – Salvage Value) / Useful Life

Let‘s break this down with a specific example. Imagine your business buys a new piece of equipment for $100,000. You estimate that the equipment will last for 10 years and have a salvage value of $10,000 at the end of that time.

Using the formula above, the annual straight line depreciation expense would be:

($100,000 – $10,000) / 10 = $9,000

This means that each year, you would record a depreciation expense of $9,000 for this piece of equipment. After 10 years, the total depreciation expense would be $90,000 (10 years x $9,000 per year).

At that point, the asset would be considered "fully depreciated" and have a book value equal to its salvage value of $10,000. The book value represents the asset‘s cost minus its accumulated depreciation.

Assumptions of Straight Line Depreciation

While straight line depreciation is the easiest depreciation method to understand and use, it‘s important to be aware of the assumptions behind it. The main assumptions of the straight line method are:

1. The asset‘s economic usefulness is the same each year over its life.
2. The asset‘s maintenance and repair costs are the same each year.
3. The asset will be used for its full estimated useful life.

In reality, these assumptions may not always hold true. Some assets may lose their value or become obsolete more quickly than originally estimated. Others may require more maintenance and repairs as they age, making the economic benefits uneven from year to year.

Despite these limitations, straight line depreciation remains popular because of its simplicity. It may not always match an asset‘s economic reality perfectly, but it provides a reasonable and consistent way to allocate an asset‘s cost over time.

Determining an Asset‘s Useful Life

One of the most important pieces of the straight line depreciation formula is an asset‘s useful life. This is your estimate of how many years you expect to use the asset productively in your business before it wears out or becomes obsolete.

The useful life you choose should be based on your specific plans for using the asset, not necessarily how long the asset could theoretically last. Some key factors to consider are:

• How much you plan to use the asset each year
• The quality and durability of the asset
• How well you maintain the asset
• How quickly the technology may change, making the asset obsolete

It‘s also important to understand that the useful life for tax depreciation may be different than the useful life used for your internal accounting records. For taxes, you must use the useful lives specified by the IRS for different asset classes.

Here‘s a table showing some common assets and their useful lives according to the IRS:

Asset Class	Useful Life
Office furniture	7 years
Cars and trucks	5 years
Computers and office equipment	5 years
Manufacturing equipment	7-10 years
Residential rental property	27.5 years
Commercial buildings	39 years

As you can see, the IRS tends to assign shorter useful lives than what you may use for accounting purposes. This lets businesses take higher depreciation expense deductions and lower their tax bill more quickly.

However, it‘s usually better to use longer useful lives for your own books to avoid overstating depreciation and distorting your true profitability. Many accountants recommend depreciating assets over their actual expected economic life, rather than the shorter tax life.

Estimating an Asset‘s Salvage Value

Along with useful life, the other key input in the straight line depreciation formula is salvage value. This represents your estimate of what the asset will be worth at the end of its useful life.

Theoretically, an asset‘s salvage value is the amount you could get by selling or scrapping the asset once you‘re done using it. If you think the asset will still have some economic value at that point, you should factor that into your annual depreciation expense calculation.

However, in practice, many businesses choose to ignore salvage value or set it at $0. They do this either because the salvage value is expected to be minimal or because it‘s too difficult to estimate what the value will be that far in the future.

If you do choose to include a salvage value, here are some factors to consider:

• The asset‘s expected condition at the end of its useful life
• The costs you may incur to remove or dismantle the asset
• The current and projected future market demand for the asset
• Technological changes that could make the asset obsolete

Keep in mind that salvage values are really a "best guess" and may change over the life of an asset. It‘s a good idea to periodically review your salvage value estimates and adjust them if needed based on new information.

Here‘s an example of how salvage value fits into the straight line depreciation calculation:

Let‘s say your company buys a piece of equipment for $50,000. You estimate its useful life to be 8 years and its salvage value to be $2,000. Using the straight line formula, the annual depreciation expense would be:

($50,000 – $2,000) / 8 years = $6,000

This means each year, you would record $6,000 of depreciation expense. After 8 years, you will have recorded a total of $48,000 in depreciation ($6,000 per year x 8 years), and the asset would have a book value of $2,000, equal to its estimated salvage value.

Straight Line vs. Accelerated Depreciation

While straight line is the simplest and most commonly used depreciation method, it‘s not the only option. Some businesses choose to use accelerated depreciation methods, such as double declining balance or sum of the years‘ digits.

Under accelerated depreciation, a larger portion of an asset‘s cost is expensed in the early years of its life and a smaller portion is expensed in later years. This can be beneficial for tax purposes because it lets you take bigger deductions upfront, lowering your current year tax bill.

However, accelerated depreciation has some drawbacks:

1. It‘s more complicated to calculate than straight line depreciation.

2. It can make your financial statements less consistent and harder to compare across periods.

3. If an asset becomes obsolete or is sold before the end of its useful life, you may end up overstating depreciation expense.

In general, most businesses stick with straight line depreciation for simplicity and consistency. The main exception is when a company wants to take advantage of accelerated depreciation for tax purposes.

In that case, the business would typically keep two sets of depreciation records: one using straight line for their internal books and one using an accelerated method for taxes. The difference between the two is recorded as a deferred tax asset or liability on the balance sheet.

How Depreciation Impacts Financial Statements

Depreciation expense flows through to several key financial statements: the income statement, balance sheet, and cash flow statement. Here‘s a quick overview of how depreciation is recorded on each:

Income Statement

Depreciation expense is recorded on the income statement each period and directly reduces a company‘s net income. For example, if a company has $100,000 in revenue and $20,000 in depreciation expense, its net income would be $80,000 ($100,000 – $20,000), assuming no other expenses.

Balance Sheet

On the balance sheet, an asset‘s cost is recorded in a fixed asset account when it‘s purchased. Each year, the accumulated depreciation (the total depreciation expensed since the asset was acquired) is recorded in a contra-asset account and subtracted from the fixed asset account to arrive at the asset‘s net book value.

For example, if a company buys a $100,000 asset and records $10,000 in depreciation each year, after three years the fixed asset account would still show a $100,000 cost, but the accumulated depreciation account would have a $30,000 credit balance. The net book value of the asset would be $70,000 ($100,000 – $30,000).

Cash Flow Statement

Depreciation expense is recorded as a positive amount on the cash flow statement in the operating activities section. This is because depreciation is a non-cash expense – no money actually leaves your bank account when you record depreciation.

By adding depreciation expense back to net income, you can see how much cash your business generated from its operations, separate from the depreciation accounting entry.

Here‘s an example cash flow statement:

Cash Flow Statement for the Year Ended 12/31/XX 

Cash flows from operating activities:
 Net income:          $100,000
 Depreciation expense:     $20,000
                     --------
Net cash provided by operating activities: $120,000

This shows that while the company reported $100,000 in net income, it actually generated $120,000 in cash from its core business operations.

The Bottom Line on Straight Line Depreciation

Depreciation is a core accounting concept that all business owners need to understand. It allows you to spread out the cost of long-term assets over their useful lives, providing a more accurate picture of your profitability.

The straight line method is the most straightforward way to calculate depreciation expense. By expensing an equal amount each period, you can easily match an asset‘s cost to the revenues it helps generate.

While accelerated depreciation methods can provide a tax benefit, most accountants recommend sticking with straight line depreciation for your internal books. The consistent, even allocation of costs over time makes your financial statements easier to understand and compare.

Of course, no matter which method you use, depreciation involves some important estimates and assumptions. To make sure your depreciation expense is as accurate as possible, be sure to:

• Keep detailed records of all your depreciable assets, including purchase dates, costs, and estimated salvage values
• Assign a reasonable useful life to each asset based on how long you actually plan to use it in your business
• Review your depreciation schedule and useful life estimates periodically and make adjustments as needed
• Consider the tax implications of your depreciation choices and whether maintaining separate books for taxes makes sense

By understanding how depreciation works and following these best practices, you‘ll be able to make better decisions about investing in long-term assets and keep your financial statements on solid ground.

Remember, depreciation isn‘t just an accounting entry – it‘s a reflection of the very real costs of using assets to generate revenue in your business. By getting depreciation right, you‘ll have a clearer picture of your true profitability and be able to plan for the future with more confidence.