What it means
Obsolete stock is not the same as slow-moving stock, though the two are often reported together. Slow-moving stock will eventually sell; obsolete stock will not sell at anything like full price, and holding on to it only adds storage cost to a loss that has already happened.
Accounting rules require inventory to be carried at the lower of cost and net realisable value, which means obsolete items must be written down as soon as they are identified. That write-down hits profit immediately, so businesses that put off the decision are quietly carrying an overstated balance sheet and an overstated profit figure.
The measure is most useful when tracked as a trend and broken down by category. A jump in the rate for one product family usually points at a specific cause, such as a design change, a lost customer contract or a promotion that never happened.
Prevention beats measurement. Inventory ageing reports, minimum shelf-life rules on incoming goods, and a discipline of reviewing any line with no movement for six months will catch most obsolescence before the value has fully evaporated.
In practice
Real-world examples.
Example
A fashion retailer measures obsolescence at the end of each season. Last season's rate was 4%, this season's is 9%, and the buying team traces the increase to an over-order on one outerwear range after a mild autumn.
Example
A medical supplies business tracks expiry dates as its obsolescence trigger. Any batch within 90 days of expiry moves onto a clearance list automatically, which keeps the annual obsolescence rate under 2%.
Example
A machine tool manufacturer changes the design of a control unit. Finance immediately reviews the component stock for the old design, identifies $180,000 of parts with no remaining application, and books the write-down in the same quarter as the design change.
Think of it
“Obsolescence rate shows how much inventory becomes unsellable-your write-off percentage.
Formula
Calculation
Inventory obsolescence rate = (value of obsolete inventory / total inventory value) x 100
A consumer electronics distributor holds total inventory of $5,000,000 at cost. A quarterly review identifies $250,000 of stock as obsolete: superseded models, discontinued accessories and packaging for a range that has been retired.
Inventory obsolescence rate = ($250,000 / $5,000,000) x 100
= 0.05 x 100
= 5%
The accounting consequence follows straight away. If the obsolete items can be cleared to a liquidator for $60,000, the write-down is $250,000 - $60,000 = $190,000, and that amount reduces pre-tax profit in the quarter it is recognised. Carrying inventory on the balance sheet at $5,000,000 when $190,000 of it will never be recovered simply moves the loss into a future period.Case study
Seen in the real world.
Pemberton Audio is a fictional maker of hi-fi components, presented here purely as an illustrative case. It launched a new amplifier range every two years and had a habit of building components for the outgoing range right up to the launch of the replacement.
For three years running the obsolescence rate ran between 8% and 11% of a stock holding worth around $4 million, meaning $320,000 to $440,000 written off annually. Nobody had connected these write-offs to the launch cycle because they were recorded as a single line in cost of goods sold each December.
A new financial controller reported obsolescence quarterly and split it by product generation, which made the pattern obvious within two quarters. Pemberton introduced a rule that component purchasing for any range would taper from twelve months before a planned launch, and the rate fell to 3% the following year. The illustrative moral is that obsolescence is usually a purchasing decision made months earlier, not an accident discovered at year end.
Watch out
Common mistakes.
- Delaying a write-down in the hope that the stock will eventually sell, which overstates both profit and assets while storage costs keep accruing.
- Confusing obsolete stock with slow-moving stock and applying the same treatment to both, when one needs clearing and the other simply needs better forecasting.
- Reporting obsolescence once a year, which removes any chance of spotting and fixing the cause while it is still happening.
Questions
People also ask.
What obsolescence rate is acceptable?
It varies widely, with stable industrial products often under 2% and fashion or technology lines regularly reaching 5% to 10%, so your own trend matters more than any benchmark.
Is a provision the same as a write-off?
A provision is an estimated allowance against stock you expect to become unsellable, while a write-off removes specific identified items; both reduce profit, but the provision is reversible if circumstances change.
Can obsolete stock still be worth something?
Often yes, through clearance channels, spare parts demand, or recycling, and net realisable value should reflect whatever can genuinely be recovered.
From the founder's library
Take it further with the book.
Build your financial confidence beyond this definition. Shihan's full-length guide, Accounting Fundamentals, takes the same plain-English approach and turns it into a complete, practical playbook for non-finance managers, business owners and students - with chapter-end quiz answers and presentation slides included.
25% off with code MMHQ25, applied at checkout. Priced in USD - checkout may show the equivalent in your local currency.
View the book and save 25%