Accounting for Inventory | Periodic, Perpetual inventory



Accounting for Inventory Basic Rule: Inventory must be measured at lower of; Cost; or Net realizable value (NRV). NRV is usually higher than cost.
Accounting for Inventory, Introduction to cost and management accounting, Cost Estimation, High/Low, Linear Regression Analysis

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Accounting for Inventory Overview

Inventory costing methods

There are two methods of recording inventory (Inventory accounting):

  1. Periodic inventory method/period end system
  2. Perpetual inventory system

Each method uses a ledger account for inventory but these have different roles.

Methods for Recording Inventory

Methods for recording Inventory

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Periodic inventory method

This system is base on the use of two ledger accounts:

Purchase Account:

It is used to record all purchases during the year. the balance on purchase account is transferred to cost of sales, clearing the purchases account to zero.

Inventory Account:

  • It is used to record value of inventory at the beginning/end of the year.
  • Opening inventory is last year’s unused purchases.

Perpetual inventory system

In cost accounting system:

  • A separate record is kept for each inventory item, in an inventory account. There is no purchase account.
  • Inventory account is used to record all purchases and other costs associated with inventory and all issue/transfers out of inventory. These transfers might be into work in progress(if inventory account is for raw material) or cost of sales (if inventory account is for finished goods).
  • Each issue/transfers are given a cost. This is the actual cost or cost obtained from valuation method (i,e FIFO/AVCO method).

With perpetual inventory account any time the balance on inventory account is the value of inventory currently held.

Summary of journal entries under Perpetual accounting and Period end system

Particular Perpetual Inventory method Periodic Inventory method
Opening inventory Closing inventory as brought forward from last period. Closing balance on the inventory account at the end of previous period.
Purchase of inventory Purchases Debit
Payable/cash Credit
Inventory Debit
Payable/cash Credit
Freight paid Carriage inwards Debit
Payable/cash Credit
Inventory Debit
Payable/cash Credit
Return of inventory to supplier Payable Debit
Purchase returns Credit
Payable Debit
Inventory Credit
Sale of inventory Receivables Debit
Sales Credit
Receivables Debit
Sales Credit
Cost of goods sold Dr.
Inventory Cr.
Return of goods by a customer Sales returns Debit
Receivables Credit
Sales returns Debit
Receivables Credit
Inventory Dr.
Cost of goods sold Cr.
Issue of Inventory (NO ENTRY IN PURCHASE A/C) WIP Debit
Inventory Credit
Return of unused inventory from production (NO ENTRY IN PURCHASE A/C) Inventory Debit
WIP Credit
Normal loss (NO ENTRY IN PURCHASE A/C) Cost of goods sold Dr.
Inventory Cr.
Abnormal loss Abnormal loss Debit
Purchases Credit
Abnormal loss Debit
Inventory Credit
Closing Inventory SOFP Dr.
Cost of good sold Cr.
Balance on Inventory account (subject to physical count).

Accounting for Inventory: Inventory Valuation

Valuation of Inventory

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Basic Rule:
Inventory must be measured at lower of;

  • Cost; or
  • Net realizable value (NRV)

Cost Formulas

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It would be impossible to identify the actual cost for all inventory items because of the large numbers of such items.

Therefore, cost formulas are used for determining cost of group of similar items.

The following cost formulas are used:

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First in, first out (FIFO)

  • Large and expensive items are readily recognizable but cost of similar items are impossible to identify.
  • To establish the cost of inventory using first in first out inventory method (FIFO) it is necessary to record:
Received Issued
Date Units Price Date Units Price
  • This approach assumes that the first inventory sold is always the inventory bought earliest date.

This means closing inventory is always assumed to be the most recent purchase.

Weighted Average cost (AVCO)

Weighted Average cost (AVCO)

  • This approach assumes that all units are issued at the current weighted average cost per unit.
  • A new average cost is calculated whenever more items are purchased and received in stores as:

Cost in store + New items cost
No. of units in stores + New units

Costing of Issues from inventory and Inflation


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As a general rule, during a period of high inflation the different methods of inventory valuation will give significantly different values for cost of sales and closing inventory.

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First in, first out (FIFO)

  • With FIFO during a period of high inflation cost of sales will be lower than current replacement cost of materials used and the closing inventory should be close to current value, since they are the units bought most recently.
  • The inverse is also correct when prices are falling.

Weighted Average cost (AVCO)

With AVCO during a period of high inflation, the cost of sales will be higher and value of closing inventory lower than FIFO valuation.

Accounting for inventory

Inventory costing methods pdf

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