COGS (Cost of Goods Sold) is the direct cost of the products a business actually sold in a period — materials, direct labour, and production overhead, but not rent, marketing, or admin. The formula is Opening Inventory + Purchases − Closing Inventory. It sits on your profit and loss statement, reduces your taxable income, and drives your gross profit margin.
If you’ve ever looked at strong sales and wondered why so little of it shows up in your bank account, COGS is usually the missing piece. This guide breaks down what it is, how to calculate it correctly, how it interacts with GST and the ATO’s trading stock rules, and the mistakes that trip up most small business owners.
What Does COGS Mean?
COGS stands for Cost of Goods Sold — the direct cost of producing or buying the specific items a business sold during a set period. It answers one question: what did it actually cost to get those sold goods ready for sale?
It’s a direct cost, not a cost of “running the business.” That distinction is what most people get wrong, and it’s the difference between an accurate gross profit figure and a distorted one.
COGS vs. Cost of Sales – Are They the Same Thing?
Yes, in most small business contexts. “Cost of Sales” and “COGS” describe the same calculation — the direct cost of what you sold. Retailers and product businesses tend to say COGS; service and hybrid businesses (who might include some direct service delivery costs) more often say “Cost of Sales.” Your accounting software may use either term — check your chart of accounts rather than assuming they’re different line items.
What’s Included and Excluded from COGS
| Usually included in COGS | Usually excluded from COGS |
| Raw materials | Advertising and marketing |
| Wholesale/purchase cost of stock | Office rent |
| Direct production labour | Administrative and management salaries |
| Factory/production overhead | Software subscriptions (unless production-specific) |
| Freight-in (getting stock to you) | Freight-out (delivering to the customer) |
| Packaging used in production | General office supplies |
Two items worth flagging because they’re the most commonly misclassified:
- Freight-in vs freight-out. Shipping to receive inventory is COGS. Shipping to deliver a finished order to your customer is an operating expense.
- Unsold or spoiled inventory. Stock you produced but haven’t sold yet isn’t COGS until it sells (or is written off).
COGS vs. Operating Expenses
| Aspect | COGS | Operating Expenses |
| What it includes | Direct costs of making/buying the product | Indirect costs of running the business |
| Examples | Materials, direct labour, production overhead | Rent, utilities, admin salaries, marketing |
| Where it appears | Subtracted from revenue to get gross profit | Subtracted from gross profit to get net profit |
| Tax treatment | Reduces taxable income via cost of sales | Deductible, but reported separately |
Mixing the two doesn’t just look untidy – it distorts your gross margin, which lenders, investors, and your own pricing decisions all rely on.
COGS, GST, and the ATO
This is the part most COGS guides skip, and it’s where Australian businesses actually get tripped up.
The ATO requires GST-registered businesses to value trading stock excluding the GST component when it’s a credit you’re entitled to claim — so your COGS calculation should use GST-exclusive figures, not the GST-inclusive amount on your supplier invoice. The ATO also allows three methods for valuing trading stock at year-end: cost, market selling value, or replacement value, and you can choose a different method for different stock items each year (see the ATO’s Valuing trading stock guidance).
Practical implications:
- Keep your COGS workings GST-exclusive to avoid overstating costs.
- Your closing stock value from one financial year automatically becomes your opening stock value for the next — reconcile it before you close the books.
- If you’re a retailer using a simplified GST accounting method (common in food retail), your trading stock purchase records feed directly into that calculation, so COGS accuracy has a GST compliance flow-on effect, not just an income tax one.
This is general information, not tax advice – confirm your specific trading stock valuation method with a registered tax agent or BAS agent.
Why COGS Accuracy Matters
- Gross profit and pricing. If COGS is wrong, your gross margin is wrong, and every pricing decision built on it inherits the error.
- Tax reporting. COGS reduces taxable income. Under- or over-stating it can mean paying the wrong amount of tax, or drawing ATO attention at audit.
- Cash flow and inventory planning. COGS trends tell you when input costs are creeping up before they erode your margin.
- Lending and valuation. Banks, investors, and buyers assess gross margin as a core signal of business quality — inconsistent COGS reporting is a red flag in due diligence.
The COGS Formula, Step by Step
COGS = Opening Inventory + Purchases − Closing Inventory
- Start with the value of inventory on hand at the beginning of the period.
- Add everything purchased or produced during the period (including freight-in and direct labour where relevant).
- Subtract the value of inventory still on hand at the end of the period.
What’s left is the cost of what you actually sold — not what you bought, and not what you’re still holding.
Three Worked Examples
Generic examples don’t show how COGS behaves differently by business model, so here are three side by side.
Example 1: E-commerce retailer
- Opening inventory: $20,000
- Purchases during the year: $80,000
- Closing inventory: $25,000
- COGS = 20,000 + 80,000 − 25,000 = $75,000
Example 2: Small manufacturer
- Opening inventory (raw materials + WIP): $45,000
- Purchases, direct labour, and factory overhead: $25,000
- Closing inventory: $10,000
- COGS = 45,000 + 25,000 − 10,000 = $60,000
Example 3: Dropshipping / low-inventory seller
- Opening inventory: $0 (stock is ordered per sale)
- Purchases (unit cost × units sold, plus freight-in): $18,000
- Closing inventory: $0
- COGS = 0 + 18,000 − 0 = $18,000
Notice how in Example 3, COGS collapses to purchases alone when a business holds little or no stock — a common source of confusion for dropshippers who expect the full three-part formula to apply.
Inventory Valuation Methods
The method you choose changes your COGS figure, so consistency matters as much as the method itself.
| Method | How it works | Effect in Australia |
| FIFO (First In, First Out) | Oldest stock is assumed sold first | Common and compliant; tends to show lower COGS and higher taxable profit when prices are rising |
| LIFO (Last In, First Out) | Newest stock is assumed sold first | Not permitted under Australian tax law — mentioned here only so you know to avoid it |
| Weighted Average Cost | Total cost spread evenly across all units | Smooths out price fluctuations; popular with high-volume sellers |
| Specific Identification | Actual cost of each individual item tracked | Used for low-volume, high-value, or unique items (e.g. vehicles, custom furniture, jewellery) |
Fixed vs. Variable COGS
Most guides treat COGS as one lump figure, but splitting it helps with pricing decisions:
- Variable COGS moves with sales volume — the unit cost of stock, transport per order, packaging per item.
- Fixed COGS stays roughly constant regardless of volume within a range — a factory lease tied directly to production, or a salaried production supervisor.
Knowing the split tells you how much your cost per unit will actually improve if you scale, versus costs that won’t budge until you hit the next capacity threshold.
Common Mistakes in COGS Calculation (and How to Fix Them)
| Mistake | Fix |
| Lumping operating expenses into COGS | Map every cost to “direct” or “indirect” before it hits the ledger |
| Forgetting freight-in | Add a dedicated freight-in line in your chart of accounts |
| Wrong inventory counts | Do a physical stocktake at period end, don’t rely on system estimates alone |
| Switching valuation methods inconsistently | Pick one method per stock category and document why you’d ever change it |
| Not writing off dead or spoiled stock | Review slow-moving inventory each quarter and write off promptly |
| Using GST-inclusive figures | Strip GST out before it enters your COGS workings |
Tools That Make This Easier {#tools}
You don’t have to calculate COGS by hand in a spreadsheet forever. Most Australian accounting platforms (Xero, MYOB, QuickBooks) can automate COGS from your inventory and purchase records once your chart of accounts correctly separates direct from indirect costs — the setup work described above is what makes the automation trustworthy. If you’re evaluating software, ask specifically whether it supports your chosen valuation method (FIFO or weighted average) and whether it reports COGS GST-exclusive by default.
Get Your Freight-In Costs Right With iSend {#isend-cta}
Freight-in is one of the most commonly missed COGS inputs — and one of the easiest to get wrong when you’re juggling multiple carriers and suppliers. iSend gives Australian e-commerce and retail businesses a single dashboard to manage multi-carrier shipping, import and customs costs, and fulfilment, so your landed cost per unit is accurate before it ever hits your COGS calculation. If freight-in visibility is the gap in your current setup, explore iSend’s shipping and fulfilment solutions.
FAQs
What does COGS mean in accounting? COGS is the direct cost of producing or buying the goods a business sold in a given period. It excludes indirect costs like rent, admin, or marketing, and is used to calculate gross profit.
Is COGS the same as Cost of Sales? Yes — they refer to the same calculation, just different naming conventions depending on industry and software.
How often should you calculate COGS? At minimum, every time you prepare financial statements — monthly or quarterly for active inventory businesses, and always at financial year-end for tax reporting.
Is shipping included in COGS? Freight-in (getting stock to your business) is included. Freight-out (delivering to your customer) is an operating expense, not COGS.
Is packaging included in COGS? Packaging used in production or to prepare goods for sale is generally included. Generic office or admin packaging is not.
Does GST affect my COGS figure? Yes — COGS should generally be calculated GST-exclusive if you’re entitled to claim GST credits on your purchases, per ATO trading stock valuation rules.
Can I use LIFO in Australia? No. LIFO isn’t accepted under Australian tax law. Use FIFO, weighted average, or specific identification instead.
What if I have no inventory (services or dropshipping)? The formula still applies, but opening and closing inventory may be zero or minimal, so COGS often reduces to direct purchase or fulfilment costs for the period.
Conclusion
COGS isn’t just a line on your profit and loss statement — it’s the number that tells you whether your sales are actually translating into profit. Get the direct-vs-indirect split right, keep it GST-exclusive, pick a valuation method and stay consistent, and recalculate it as often as you make pricing or inventory decisions. That’s the difference between a COGS figure that’s technically present in your books and one you can actually run a business on.
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