Annuity Depreciation Calculator

Compute annual depreciation charges using the annuity (sinking fund) method. Enter asset cost, salvage value, useful life, and discount rate to generate a full depreciation schedule, accumulated depreciation, book value, and an interactive chart.

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All monetary values in USD. Discount rate is the annual interest rate used for the annuity calculation.
? Machinery: Cost $120k, Salvage $15k, 8 yrs, 6%
? Vehicle: Cost $45k, Salvage $5k, 5 yrs, 7%
? Building: Cost $500k, Salvage $80k, 20 yrs, 5%
? Equipment: Cost $25k, Salvage $2k, 4 yrs, 10%
? High Rate: Cost $80k, Salvage $8k, 6 yrs, 15%
Privacy first: All computations are performed locally in your browser. No data is transmitted or stored on our servers.

Understanding Annuity Depreciation

The annuity method of depreciation, also known as the sinking fund method, is a depreciation technique that recognizes the time value of money. Unlike straight‑line or declining‑balance methods, the annuity method assumes that the asset's cost is a capital investment that could have earned interest elsewhere. Therefore, the annual depreciation charge consists of two components: a depreciation element and an interest element on the declining book value.

This method is particularly relevant for assets where the cost of capital is significant, such as long‑term infrastructure projects, real estate, and capital‑intensive machinery. It aligns the depreciation expense with the economic reality that funds tied up in an asset have an opportunity cost.

Annual Payment = (C · (1+r)n − S) · r⁄(1+r)n − 1

Where C = initial cost, S = salvage value, r = discount rate per period, n = number of periods.

Key Characteristics

  • Constant Annual Payment: The total annual charge (depreciation + interest) remains constant over the asset's life.
  • Interest Component: Each year, interest is calculated on the opening book value. The remaining portion of the payment reduces the book value.
  • Book Value Pattern: The book value declines more slowly in early years (because interest is higher) and more rapidly in later years.
  • Salvage Value: The method ensures that the book value exactly equals the salvage value at the end of the useful life.
Case Study: Capital Equipment Acquisition

A manufacturing company purchases a CNC machine for $100,000 with an expected salvage value of $10,000 after 5 years. The company's cost of capital is 8%. Using the annuity method, the annual payment is calculated as:
($100,000 · (1.08)5 − $10,000) · 0.08 / ((1.08)5 − 1) = $23,341.90

This annual payment remains constant. In year 1, interest on the opening book value ($100,000) is $8,000, so the depreciation element is $15,341.90. In year 5, interest on the opening book value (~$22,898) is about $1,832, so the depreciation element is $21,510. The book value declines to exactly $10,000 at the end of year 5.

This approach provides a more economically accurate representation of the asset's consumption, especially when the cost of capital is material.

Annuity vs. Other Depreciation Methods

Straight‑Line

Equal annual depreciation. Ignores time value of money.

Simple & widely used
Declining Balance

Accelerated depreciation; higher expense in early years.

Tax‑advantaged
Annuity (Sinking Fund)

Constant total charge; includes interest on book value.

Time‑value aware
Sum‑of‑Years‑Digits

Accelerated; decreasing annual depreciation.

Matches usage patterns

When to Use the Annuity Method

  • Long‑lived assets where the opportunity cost of capital is significant (e.g., real estate, power plants).
  • Regulated industries (utilities, telecom) where depreciation is used to set rate bases.
  • Internal management accounting to reflect the true economic cost of asset usage.
  • Capital budgeting when comparing projects with different asset lives and salvage values.

Mathematical Derivation

The annuity depreciation method is derived from the present value of an annuity formula. The asset's cost is the present value of the annual payments plus the present value of the salvage value. Equivalently, we can solve for the annual payment A such that:

C = A · 1 − (1+r)−n⁄r + S · (1+r)−n

Solving for A gives:

A = (C − S · (1+r)−n) · r⁄1 − (1+r)−n

This is algebraically equivalent to:

A = (C · (1+r)n − S) · r⁄(1+r)n − 1

Each year, the interest component is r · BVt−1, and the depreciation component is A − r · BVt−1. The book value then follows:

BVt = BVt−1 − (A − r · BVt−1) = (1+r) · BVt−1 − A

With the correct choice of A, this recurrence ensures that BVn = S.

Practical Considerations and Limitations

  • Choice of discount rate: The rate should reflect the firm's cost of capital or the return that could be earned on alternative investments. Using an incorrect rate can distort depreciation charges.
  • Tax implications: The annuity method is not always accepted for tax reporting; many jurisdictions require straight‑line or MACRS for tax purposes. However, it can be used for internal financial reporting and managerial decision‑making.
  • Complexity: Compared to straight‑line, the annuity method is more complex to compute and explain to stakeholders. However, our calculator handles the complexity automatically.
  • Asset usage pattern: If an asset's usage is highly uneven, other methods (e.g., units‑of‑production) may be more appropriate.

Frequently Asked Questions

Straight‑line depreciation allocates an equal amount of the depreciable base each year, ignoring interest. Annuity depreciation includes an interest charge on the book value, resulting in a constant total annual charge but with a depreciation component that increases over time.

Because the interest component is higher in early years (calculated on a larger opening book value). A larger portion of the constant annual charge goes toward interest, leaving less to reduce the principal (book value).

Yes. Simply set the salvage value to 0. The calculator will depreciate the full cost over the useful life.

The discount rate should reflect the firm's weighted average cost of capital (WACC) or the return that could be earned on an alternative investment of similar risk. For regulated utilities, it may be prescribed by the regulator.

GAAP does not specifically require or prohibit the annuity method. However, it is less commonly used than straight‑line or accelerated methods for external reporting. It is more frequently used for internal management accounting and rate‑making.

If estimates change, the depreciation schedule should be revised prospectively. The remaining depreciable base is spread over the remaining useful life using the same annuity formula with the updated parameters.

Built on sound financial principles – This tool implements the annuity depreciation method as described in standard accounting and finance literature (e.g., Kieso, Weygandt, Warfield, Intermediate Accounting; Brealey, Myers, Allen, Principles of Corporate Finance). The formulas are derived from time‑value‑of‑money concepts and have been verified against authoritative sources. Reviewed by the GetZenQuery tech team, last updated July 2026.

References: Investopedia – Annuity Method of Depreciation; Kieso, D. E. et al. Intermediate Accounting, 18th ed.; Wikipedia – Depreciation.