Inventory Increases by $10: Three Statements Interview Answer

"Inventory increases by $10. Walk me through the three financial statements." tests working capital linkages. Unlike depreciation, inventory is a balance sheet cash use when you buy stock that has not yet hit COGS. Interviewers like this because it looks easy and still catches people who invent a fake P&L hit.

The short answer

"If inventory increases by 10 and it is a cash purchase that has not been sold, the income statement does not change. On the cash flow statement, the inventory increase is a working capital outflow, so cash is down 10. On the balance sheet, inventory is up 10 and cash is down 10."

Lock assumptions

• You purchased $10 of inventory with cash (or on terms; see variants)
• None of it has been sold yet, so COGS and revenue are unchanged
• No tax effect in the base case because net income is unchanged

Say the assumptions out loud before you link statements. Ambiguity about cash vs AP is half the trap.

Base walkthrough (cash purchase, unsold)

IS: no change
CFO: -10 from inventory build
BS: Inventory +10; Cash -10

Why this is not like depreciation

Variant: bought on account (AP also +$10)

If inventory +10 and accounts payable +10:

• IS still unchanged
• CFO: inventory use -10 and AP source +10 net to 0 in NWC
• BS: Inventory +10, AP +10

Cash unchanged. This is how interviewers check whether you understand NWC nets.

Variant: financed with the revolver

Inventory +10, revolver +10, cash flat:

• IS unchanged
• CFS: inventory use in CFO; revolver draw in CFF
• BS: Inventory +10, Debt +10

Do not hide the draw inside CFO. Separate operating WC from financing.

Variant: inventory sold later

When sold, COGS rises, inventory falls, and if sold for cash above cost you also book revenue and tax. Do not jump there unless asked. Keep the "increase by $10" question clean first. If they extend the story, walk COGS, tax, and the inventory decrease as a WC source when the asset leaves.

LBO and FCF intuition

Inventory builds consume free cash flow even when EBITDA looks fine. Seasonal businesses can show ugly FCF in build months and release cash when inventory turns. In an LBO, underwriting perpetual inventory efficiency gains is a common soft assumption. Ask whether growth requires higher inventory days or safety stock.

Common traps

1. Reducing net income when inventory is only purchased
2. Putting the inventory change in CFI because "it is an investment"
3. Forgetting the AP offset when the prompt includes payables
4. Mixing inventory build with inventory write-down (write-down is a different drill)
5. Saying cash is unchanged in the pure cash purchase case

30-second verbal

"If inventory increases by 10 and it is a cash purchase that has not been sold, the income statement does not change. On the cash flow statement, the inventory increase is a working capital outflow, so cash is down 10. On the balance sheet, inventory is up 10 and cash is down 10. If AP also rises 10, cash can be flat."

Follow-ups

1. Inventory up $10, AP up $10
2. Inventory up $10 financed with the revolver
3. How does inventory build show up in FCF for an LBO?
4. Inventory write-down of $10 after the build
5. Negative working capital businesses that grow AP faster than inventory / AR

Working capital sign fluency

Keep the operating capital signs next to this drill:

• AR up: use of cash
• Inventory up: use of cash
• AP up: source of cash
• Accrued liabilities up: source of cash

Inventory up is the company funding stock ahead of sales. Growing firms can burn cash in inventory even with strong EBITDA. That is why linking questions and LBO FCF bridges love this example.

Practice ladder

Do these aloud in order:

1. Inventory +10 cash
2. Inventory +10, AP +10
3. AR +10 (cash sale not collected)
4. Accrued expense +10
5. Depreciation +10
6. Inventory write-down

Then read Working Capital Interview Questions and Accounts Payable +10.