Perpetual inventory: when your books should follow your shelf
Perpetual inventory makes your books follow the shelf. What it changes, why switching it on mid-year needs an opening entry, and how to tell if you need it.
For owners whose stock value and balance sheet have stopped agreeing · 3 min read · updated
In short
- Periodic accounting works out cost of goods sold by counting at period end; perpetual posts it on every movement.
- Perpetual is what makes stock value and the balance sheet agree.
- Switching on mid-year needs an opening entry for stock already held, or profit is misstated by that value.
- The clean moments to switch are the start of a financial year or straight after a full count.
- Perpetual does not replace the physical count; it turns the count into a check that reveals shrinkage.
Periodic and perpetual, plainly
Under a periodic system, purchases go to an expense account as you buy them. Nobody knows the cost of goods sold until somebody counts the stock at period end and works backwards: opening stock plus purchases minus closing stock.
Under a perpetual system, every movement posts as it happens. A purchase increases an asset rather than an expense. A sale moves that cost out of the asset and into cost of goods sold, on the day of the sale.
The practical difference: with perpetual inventory you know your margin on Tuesday. Without it you know it after the count, and the count is where a year of small errors arrives at once.
What it fixes
The symptom people describe is "my stock report says ₹8 lakh and my balance sheet says nothing". That is periodic accounting working as designed — the stock ledger and the books were never connected, so they cannot disagree, because they were never comparing.
Perpetual makes them one thing. Shrinkage becomes visible as it happens rather than as a residue at year end. And cost of goods sold stops being a plug figure, which matters the first time somebody asks why gross margin moved.
Why you cannot just switch it on
This is the part that is skipped in most explanations. If you turn perpetual inventory on halfway through a year, you have stock on the shelf that was already expensed under the old method. Unless somebody posts an opening entry moving that value onto the asset side, the balance sheet gains inventory that no entry created, and your profit for the year is wrong by the value of everything you were already holding.
That is why any system that flips this silently should worry you. In Dailybuz it stays off until a workspace chooses it, precisely because the choice needs an opening entry to go with it.
The clean moments to switch are: at the start of a financial year, or immediately after a full physical count that gives you a defensible opening value.
Do you need it yet?
You probably do not, if you hold little stock, sell services, or your accountant is happy with an annual count and your bank is not asking questions.
You probably do, if any of these are true: you are asked for monthly management accounts, you carry stock worth more than a month of revenue, you have more than one location, or you have ever argued about what gross margin actually was.
What it does not fix
Perpetual inventory does not remove the physical count. It changes what the count is for: instead of producing the cost of goods sold, it checks it. A count under perpetual is a reconciliation, and the difference it finds is shrinkage — which is the number you actually wanted.
Common questions
- Is perpetual inventory required in India?
- No accounting standard mandates it. It is a bookkeeping method, not a compliance requirement. What is required is that your closing stock is valued correctly and consistently, which either method can do.
- Does perpetual inventory mean I stop counting stock?
- No, and any vendor who says so is selling. Under perpetual, the count stops being the source of cost of goods sold and becomes the check on it. The gap it finds is shrinkage, which a periodic system hides inside the cost of what sold.
- Can I switch from periodic to perpetual inventory mid-year?
- You can, but only with an opening entry that moves the value of stock already on hand onto the balance sheet. Without it, profit for the year is misstated by that value. The start of a financial year, or straight after a full count, is the clean moment.