Double Declining Balance Calculator
Calculate accelerated depreciation using the double declining balance method with automatic switch to straight line. Generate a full schedule and export to Excel.
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Double Declining Method Formula
The double declining balance (DDB) method is an accelerated depreciationapproach that applies a rate equal to twice the straight line rate to the asset's remaining book value each year.
The method automatically switches to straight line when the straight line calculation gives a higher annual deduction — maximizing total tax benefit.
How to Calculate Accumulated Depreciation — DDB
Unlike straight line depreciation, accumulated depreciation under DDB grows faster in early years and slows as the book value decreases toward the salvage value.
| Year | Book Value (Start) | DDB Deduction (40%) | Book Value (End) |
|---|---|---|---|
| Year 1 | $50,000 | $20,000 | $30,000 |
| Year 2 | $30,000 | $12,000 | $18,000 |
| Year 3 | $18,000 | $7,200 | $10,800 |
| Year 4 | $10,800 | $4,320 → SL | $6,480 |
| Year 5 | $6,480 | $1,480 → SL | $5,000 (Salvage) |
*Example assumes $50,000 cost, $5,000 salvage, 5-year life (40% DDB rate). Switch to straight line in Years 4–5 for maximum deductions.
When to Use Double Declining Balance
✓ Use DDB When:
- Asset value declines rapidly in early years
- You want larger deductions sooner
- Asset is technology or machinery
- You need to reduce taxable income quickly
✗ Avoid DDB When:
- Asset value is consistent over its life
- You expect higher income in later years
- Asset is real estate (use straight line)
- Consistent expense reporting is required