Inventory Ageing Analysis: Find the Stock That's Quietly Costing You
An inventory ageing analysis groups every SKU by how long it has sat unsold, so you catch slow movers while there is still time to act instead of finding out at stocktake. This walks through building the report from your own data, reading each ageing bucket, deciding what to do with each one — mark down, bundle, stop reordering, return to supplier — and keeping a live system flagging ageing stock automatically.
Inventory ageing analysis groups the stock you hold by how long it has been in your business, then values each age band at cost. It turns a single stock value into a clear picture of what is fresh, what is slowing and what has barely moved for months.
The practical problem is timing. Many businesses only notice old stock at the year-end count, when supplier return windows have closed, seasons have passed and the remaining exit is a deep discount. A monthly ageing report gives buyers, warehouse staff and finance the same early warning while there are still sensible options.
Stock that sits untouched for months ties up cash and space long before it appears as a loss. Illustrative photograph, not an OpsMavix project.
Image credit: Tim Mossholder, Unsplash License. No edits.
Key Takeaways
- Inventory ageing measures how long stock has been held, by receipt layer, and values each band at cost.
- Ageing by receipt layer, using FIFO, shows old units that a single last receipt or last sale date hides.
- Age bands should reflect how fast each category normally sells, not one universal rule.
- Holding aged stock costs money every month, while the options for clearing it usually narrow with time.
- Ageing is evidence for provisions and write-downs, but the accounting test is the lower of cost and net realisable value.
- A useful system ages stock automatically, flags lines crossing a threshold and records the decision taken.
In this guide:
- 1. Understand What Inventory Ageing Analysis Means
- 2. Choose How to Measure Stock Age
- 3. Set Age Bands That Fit Your Stock
- 4. Build the Ageing Report Step by Step
- 5. Count the Holding Cost of Aged Stock
- 6. Decide an Action for Every Age Band
- 7. Link Ageing to Provisions and Stock Valuation
- 8. Set Reporting and System Requirements
- Frequently Asked Questions
- How OpsMavix Can Help
1. Understand What Inventory Ageing Analysis Means
A direct definition
Inventory ageing analysis is a report that splits stock on hand into time bands, such as 0 to 30 days or over 365 days, according to how long it has been held. For each band it shows the number of lines, the units and, most importantly, the value at cost.
It is similar in spirit to an aged debtors report. Aged debtors show which money owed to you is going stale; an ageing report shows which money you have already spent on stock is going stale on a shelf.
What it answers and what it does not
| Question | Does ageing answer it? | Better companion measure |
|---|---|---|
| How much cash sits in stock older than 90 days? | Yes | None needed |
| Which old lines carry the most value? | Yes, when sorted by value | ABC analysis for ranking |
| How fast does stock sell overall? | Only indirectly | Inventory turnover ratio |
| Is a line still selling, just slowly? | Partly | Slow-moving inventory review |
| What do we do with stock that has stopped? | No, it only flags it | Dead stock management |
Ageing is an early-warning view. Slow-moving analysis looks at sales rates, and dead stock management deals with lines that have already stalled. Used together, they show where stock is heading before the loss is fixed.
2. Choose How to Measure Stock Age
Three common age bases
| Age basis | How age is calculated | Strength | Weakness |
|---|---|---|---|
| Receipt date per layer | Report date minus the date each remaining batch or receipt arrived | Shows the true age of units still held | Needs reliable goods-in dates for every receipt |
| Last receipt date per line | Report date minus the most recent delivery | Simple to extract | A fresh delivery makes the whole line look new |
| Last movement date per line | Report date minus the last sale or issue | Shows dormancy, useful for spotting dead lines | One small sale makes a large old holding look active |
For most businesses, ageing by receipt layer is the most honest basis, with last movement date as a second column. Receipt dates depend on a disciplined goods receiving process, because a missing or late receipt date produces a wrong age.
Use FIFO layers to find the real age
If you assume the oldest units leave first, the units still on hand are the most recent receipts. You work backwards from the latest delivery until the quantity on hand is used up. Whatever remains in each receipt is a layer with its own age. This mirrors the first-in, first-out cost formula, which IAS 2 lists alongside weighted average cost for ordinarily interchangeable items.
Note that this is an assumption about which units remain. If the warehouse does not actually rotate stock, the physical units may be older still. A FIFO stock rotation routine keeps the report and the shelf aligned.
Hypothetical worked example: one line, three ages
A wholesaler runs its report on 31 October 2026. Line BR-200, a steel bracket, has 260 units on hand. Recent receipts were:
| Receipt date | Units received | Unit cost | Units still on hand under FIFO | Age at 31 October | Value at cost |
|---|---|---|---|---|---|
| 15 October 2026 | 100 | £4.20 | 100 | 16 days | £420 |
| 20 August 2026 | 120 | £4.00 | 120 | 72 days | £480 |
| 2 May 2026 | 150 | £3.80 | 40 | 182 days | £152 |
| 10 February 2026 | 80 | £3.60 | 0 | Not held | £0 |
| Total | 260 | £1,052 |
The last receipt date says the line is 16 days old, and a sale yesterday would make it look active. The layer view shows 40 units, worth £152, have been held for 182 days. That is the stock that needs a decision.
3. Set Age Bands That Fit Your Stock
Start with a standard set
A common starting point is six bands: 0 to 30 days, 31 to 60, 61 to 90, 91 to 180, 181 to 365 and over 365 days. The bands should not overlap, so every layer falls into exactly one.
Adjust bands by category
What counts as old depends on how fast a category should sell. A chilled food line can be in trouble at 10 days, while a slow-turning spare part may be healthy at 120 days.
| Category type | Example bands | Why |
|---|---|---|
| Short shelf life goods | 0 to 7, 8 to 14, 15 to 30, over 30 days | Expiry arrives before monthly bands would show a problem |
| Fashion and seasonal lines | 0 to 30, 31 to 60, 61 to 90, over 90 days | Value drops sharply once the season ends |
| General wholesale lines | 0 to 30, 31 to 60, 61 to 90, 91 to 180, 181 to 365, over 365 days | A balance of early warning and detail |
| Engineering spares | 0 to 90, 91 to 180, 181 to 365, over 365 days | Low sales rates are normal and expected |
A useful rule is to set the first warning band at roughly two to three times the time a category normally takes to sell through. Days of stock on hand, from your turnover figures, gives that baseline.
Checklist for setting bands
- Bands do not overlap and cover every possible age.
- Each category has an agreed normal sell-through period.
- Expiry or best-before dates are tracked separately where they apply.
- Finance and purchasing agree the bands before the report is used for decisions.
- Band changes are recorded so month-to-month trends stay comparable.
4. Build the Ageing Report Step by Step
The process
- Extract the data. For each line: quantity on hand, unit cost and every receipt with date, quantity and cost. Use landed cost where you have it, so freight and duty are included.
- Allocate quantity to layers. Work back from the latest receipt under FIFO until on-hand quantity is used.
- Calculate age. Report date minus receipt date for each layer.
- Assign a band. Place each layer in its band.
- Value each layer. Units multiplied by unit cost.
- Summarise. Total value, units and line count per band, plus the percentage of total stock value.
- Sort the worklist. Within the older bands, list lines by value, highest first.
- Compare with last month. Look for lines and bands that have grown.
The report is only as accurate as the stock record under it. Regular cycle counts stop the report from ageing quantities that are not on the shelf.
Hypothetical worked example: the summary
A hypothetical wholesaler holds £60,000 of stock at cost. Its first layer-based ageing report shows:
| Age band | Value at cost | Share of stock value |
|---|---|---|
| 0 to 30 days | £27,000 | 45% |
| 31 to 60 days | £12,600 | 21% |
| 61 to 90 days | £7,800 | 13% |
| 91 to 180 days | £7,200 | 12% |
| 181 to 365 days | £3,600 | 6% |
| Over 365 days | £1,800 | 3% |
| Total | £60,000 | 100% |
Stock held over 90 days totals £12,600, which is 21% of stock value. Another £7,800 sits in the 61 to 90 day band and could join it next month. Those two numbers are worth tracking every month: the over 90 day value and its share of the total.
5. Count the Holding Cost of Aged Stock
What holding cost includes
Holding cost is what it costs to keep stock you have already paid for. Typical components are the cost of the capital tied up, storage space, insurance, handling, counting, damage, shrinkage and obsolescence. Rates differ widely between businesses, so build your own estimate from your own costs rather than borrowing a figure. Our guide to economic order quantity explains how holding cost is used in ordering decisions.
Every location holding aged stock is space, insurance and handling that could serve faster-moving lines. Illustrative photograph, not an OpsMavix project.
Image credit: Guilherme Mendes, Unsplash License. No edits.
Hypothetical worked example: the cost of waiting
Assume the wholesaler above estimates its holding cost at 20% of stock value per year. This is an assumption for the example, not a benchmark.
| Calculation | Amount |
|---|---|
| Stock held over 90 days | £12,600 |
| Annual holding cost at 20% | £2,520 |
| Monthly holding cost (£2,520 divided by 12) | £210 |
Holding cost is only part of the story. Consider one line with £2,000 at cost:
| Option | Recovery | Holding cost | Total loss against cost |
|---|---|---|---|
| Clear now at 85% of cost | £1,700 | £0 | £300 |
| Wait six months, then clear at 50% of cost | £1,000 | £200 (£2,000 x 20% x 6/12) | £1,200 |
In this example, waiting costs £900 more. The actual figures will differ, but the pattern is common: the later a decision is made, the fewer options remain.
6. Decide an Action for Every Age Band
Default actions by band
| Age band | Default action | Owner |
|---|---|---|
| 0 to 30 days | Normal replenishment | Purchasing |
| 31 to 60 days | Watch trend, check reorder settings | Purchasing |
| 61 to 90 days | Review demand, pause or reduce reorders, consider promotion | Purchasing and sales |
| 91 to 180 days | Agree an exit: supplier return, bundle, transfer or markdown | Sales and operations |
| 181 to 365 days | Clear actively, review value with finance | Operations and finance |
| Over 365 days | Liquidate, recycle or dispose, and agree accounting treatment | Finance and management |
The levers, roughly in order of value preserved
- Stop buying more. Check whether the line is still on automatic reorder and whether the forecast behind it is out of date.
- Return to the supplier. Only where your purchase terms allow it. Check the terms and any restocking charge before discounting.
- Transfer between locations. Stock slow in one branch or channel may sell in another.
- Bundle with a faster line. This can move units with less visible discounting.
- Mark down in steps. Agree a sequence and dates rather than one deep cut.
- Liquidate or dispose. For lines with no realistic sale, recover what you can and free the space. Disposal and recycling must follow the rules that apply to the product.
Make every decision traceable
For each line in the 91 day and older bands, record the decision, the owner, the target date and the result. A list of lines that people mean to deal with is how 90 day stock becomes 365 day stock. Where stock is written off or adjusted, use a controlled stock adjustment approval workflow so the change is evidenced.
7. Link Ageing to Provisions and Stock Valuation
The accounting test is value, not age
Age alone does not set the carrying value of stock. Under IAS 2, inventories are measured at the lower of cost and net realisable value. Under UK GAAP, FRS 102 paragraph 13.4 requires inventories to be measured at the lower of cost and estimated selling price less costs to complete and sell.
HMRC’s Business Income Manual summarises net realisable value and notes that it may fall below cost because of deterioration, obsolescence or changes in demand. It also says stock should not be valued as if it were sold in a forced sale at the reporting date.
Ageing is therefore evidence. Old stock is more likely to have a net realisable value below cost, but each case still needs a realistic estimate of selling price and costs to sell.
Hypothetical worked example: two aged lines
| Line | Age band | Units | Cost per unit | Expected selling price | Costs to sell per unit | Net realisable value per unit | Carrying value | Write-down |
|---|---|---|---|---|---|---|---|---|
| Line A | 181 to 365 days | 300 | £12 | £9 | £1 | £8 | £2,400 | £1,200 |
| Line B | 91 to 180 days | 100 | £20 | £26 | £2 | £24 | £2,000 | £0 |
Line A cost £3,600 but is expected to realise £2,400, so it is written down by £1,200. Line B is old too, but it is still expected to sell above cost, so it stays at cost of £2,000. Age flagged both lines; only the value test decides the write-down.
Age-based provision matrices
Some businesses estimate a provision using a percentage for each age band. For example, a hypothetical matrix of 10% for 91 to 180 days, 40% for 181 to 365 days and 80% for over 365 days, applied to the summary report in section 4, gives £720 plus £1,440 plus £1,440, a provision of £3,600.
A matrix is an estimation method, not a rule from the standards. In the example above, the matrix gives £1,440 for the 181 to 365 band, while the line-by-line test for Line A gives £1,200. The percentages, their basis and whether they produce a reasonable net realisable value estimate should be agreed with your accountant and reviewed against actual clearance results.
Where accounting treatment needs advice
- Choosing between line-by-line write-downs and a provision matrix.
- Reversing a write-down when prices recover.
- Disclosures, tax treatment and how write-offs are evidenced.
These depend on your framework, entity and circumstances. Consult your accountant before setting a policy. Our guide to inventory write-offs covers the operational side of removing stock that can no longer be sold.
8. Set Reporting and System Requirements
A monthly reporting routine
- Run the report at month end using the same bands and age basis.
- Review the over 90 day value and its share of total stock.
- Review the top lines by value in each older band.
- Record a decision, owner and date for each reviewed line.
- Check last month’s decisions and their results.
- Share agreed write-down evidence with finance before the accounts close.
System requirements checklist
| Requirement | Why it matters |
|---|---|
| Receipt records with date, quantity and cost per receipt or batch | Needed to calculate layer ages |
| FIFO layer allocation, or batch tracking where stock is batch-controlled | Prevents fresh deliveries hiding old units |
| Configurable bands by category | Short shelf life and slow spares need different bands |
| Valuation at cost, preferably landed cost | Keeps the report aligned with financial stock values |
| Last sale and last movement date alongside age | Separates old but selling lines from dormant ones |
| Threshold alerts when layers cross a band | Removes reliance on someone remembering to run a report |
| Supplier return window dates | Highlights recoveries before they expire |
| Decision log per line with owner and target date | Makes actions traceable and measurable |
| Month-on-month trend by band | Shows whether ageing is improving or worsening |
| Export or integration to accounting | Supplies evidence for provisions and write-downs |
Choosing the right approach
| Approach | When it fits | Limitations |
|---|---|---|
| Spreadsheet export | Small catalogues and a first look at the data | Manual, easy to break and hard to trend |
| Report in existing inventory or accounting software | The software holds receipt layers and the report meets your bands | Some tools age by last receipt only; check the method |
| Integration or reporting layer | Data sits in several systems that work individually | Needs agreed data ownership and error handling |
| Focused custom application | You need alerts, decision logs and category rules the current tools lack | Requires ownership, support and maintenance |
| Full ERP, packaged or custom | Ageing is one of many connected gaps across stock, purchasing and finance | Larger change, migration and training effort |
Before choosing, test any option with one real line that has several receipts. Confirm the tool shows the same layer ages and values you calculate by hand.
Frequently Asked Questions
What is inventory ageing?
Inventory ageing is the length of time stock has been held, usually measured from the date each remaining receipt arrived. An inventory ageing report groups stock into age bands and values each band at cost.
Is inventory ageing based on receipt date or last sale date?
Receipt date per layer shows how long the units still on hand have been held. Last sale or movement date shows dormancy. Showing both is the most useful, because a line can sell occasionally while still holding a large old layer.
Which age bands should I use?
A common start is 0 to 30, 31 to 60, 61 to 90, 91 to 180, 181 to 365 and over 365 days. Adjust bands by category so the first warning appears at roughly two to three times the normal sell-through period.
How often should I run an ageing report?
Monthly suits most businesses, aligned with month-end. Short shelf life goods may need weekly or daily checks. The trend across months is often more useful than any single report.
Does old stock have to be written down?
Not automatically. Stock is measured at the lower of cost and net realisable value under IAS 2, and at the lower of cost and estimated selling price less costs to complete and sell under FRS 102. Old stock that is still expected to sell above cost may remain at cost. Agree your policy with your accountant.
What is the difference between inventory ageing and dead stock?
Ageing is the measure; dead stock is one outcome. Ageing shows stock at every stage, from fresh to very old, so you can act before a line stops selling. Dead stock is stock with no realistic prospect of sale.
Can inventory ageing be automated?
Yes, if the system holds receipt dates, quantities and costs per receipt or batch. It can then age layers continuously, flag lines crossing a band and track the decisions taken.
Can OpsMavix build an inventory ageing system?
Yes. OpsMavix can build focused applications or a full custom ERP, and can configure or integrate suitable existing tools where those approaches fit the requirements.
How OpsMavix Can Help
OpsMavix can map how receipts, stock movements and costs are recorded today, then define what is needed to age stock reliably by layer and turn the report into tracked decisions.
That may mean improving an existing tool, connecting stock and accounting records, building an inventory automation system with ageing alerts, or supporting ecommerce inventory automation and wholesale order management where stock flows through several channels.
Contact OpsMavix with one recent stock report, the receipt records behind it and the step that creates the most rework. We can use that evidence to define requirements and a practical pilot.
Keep reading
Getting value from OpsMavix? Add us as a preferred source on Google — you'll see more of our operations content in your AI Overviews, AI Mode and Search.