In retail, inventory is both your biggest asset and your biggest risk: too much stock freezes your cash, too little drives customers away. And at tax time, inventory becomes unavoidable: it feeds directly into the cost of goods sold. Here are the foundations of healthy inventory management for a small Quebec store — operations, accounting and taxes.
Inventory in your numbers: cost of goods sold
The basic accounting and tax formula:
Opening inventory + purchases for the year − closing inventory = cost of goods sold (COGS)
COGS is deducted from your sales to establish gross margin. Direct consequence: a year-end inventory count is mandatory — without it, neither your profit nor your return (T2125/TP-80 or T2) holds up. An overstated closing inventory artificially inflates your profit (and your tax); understated, it exposes you in an audit.
Valuing your stock: average cost or FIFO
- Average cost: each item is valued at the weighted average cost of purchases. Simple, smooths price swings — the most common choice for small retailers;
- FIFO (first in, first out): the oldest units are deemed sold first. Matches the physical reality of perishable goods;
- Valuation is at the lower of cost and market value: outdated or damaged stock can be written down — a legitimate deduction too often forgotten.
Golden rule: pick a method and keep it year after year. Tax authorities take a dim view of opportunistic method changes.
The physical count: the unavoidable ritual
- At least once a year, at fiscal year-end — close the store or count outside opening hours;
- Count in pairs when possible: one counts, one records;
- Compare to theoretical stock: the gap (“shrinkage”) reveals theft, breakage, register and receiving errors;
- Cycle counts (one section per week) spread out the effort and catch discrepancies sooner.
The metrics that make or break a store
| Metric | Formula | What it reveals |
|---|---|---|
| Inventory turnover | COGS ÷ average inventory | How many times stock “turns” per year |
| Days of inventory | 365 ÷ turnover | How many days of cash sleep on the shelves |
| Gross margin by category | (Sales − COGS) ÷ sales | Which categories fund the store |
| Shrinkage | Theoretical stock − counted stock | Theft, breakage, errors — watch it as a % |
Slowing turnover = cash silting up (your cash flow budget will feel it before you do). Chronic non-sellers should be liquidated: 30% off today beats 100% unsold a year from now.
Buying intelligently
- Let the data decide: reorder based on actual sales per product, not gut feeling;
- Beware of “big volume discounts”: 10% off stock that will sleep for 8 months is a bad cash deal;
- Watch minimum order quantities and negotiate split deliveries;
- Give products codes (SKUs) from day one — you cannot manage what you cannot name.
GST/QST: the detail that changes everything
Your merchandise purchases earn ITCs/ITRs (recovered taxes), and your retail sales collect taxes under the usual rules — including zero-rated items such as basic groceries. A properly configured point of sale applies the right treatment to every item; our GST/QST guide covers the principles.
InnoBooks and retail
With InnoBooks and its point of sale (InnoBooks POS):
- ✅ Items and services coded with prices, taxes and categories;
- ✅ Sales recorded at the register, taxes calculated correctly item by item;
- ✅ Supplier purchases tracked with recoverable taxes;
- ✅ Sales reports by product and period: your best (and worst) sellers, in black and white;
- ✅ Integrated accounting: register, purchases and margins in the same system as your monthly reports.
Frequently asked questions about inventory management
I make my own products. How do I value my inventory?
A maker’s inventory includes raw materials, work in progress and finished goods — at material cost plus direct labour. Keep a simple cost-per-product calculation; your accountant will refine it.
What about unsellable stock (broken, expired, out of fashion)?
Write it down to its real value (often zero) and document it: photos, a list, the disposal date. The loss flows through your COGS — a legitimate deduction, provided you can demonstrate it.
Inventory I take for personal use?
It must be removed from COGS (and GST/QST adjusted where applicable): merchandise consumed personally is not a business expense. Record these withdrawals as they happen.
At what volume does a point of sale system become necessary?
As soon as manually tallying daily sales becomes a chore — in practice, very quickly. A POS eliminates the register-to-books double entry, makes taxes reliable and produces the per-product reports that should drive your buying.
Bottom line
Inventory is managed on three planes: physical (regular counts, shrinkage watched), financial (turnover, margins by category, liquidation of non-sellers) and tax (consistent valuation method, year-end count, accurate COGS). All three rest on the same foundation: reliable sales data, product by product.
Your store deserves better than a sales notebook. Try InnoBooks for free — point of sale, inventory and accounting in a single system.