Working Capital Interview Questions: Inventory, AR, and AP Walkthroughs

After the three-statement walkthrough, working capital is where undergrads slip. Interviewers ask what happens when inventory rises, receivables rise, or payables rise, because it tests whether you understand accrual accounting versus cash. If you can do these cold, you look fluent. If you mix up the cash impact, the rest of your technicals get discounted.

Net working capital in one line

NWC ≈ Current Operating Assets − Current Operating Liabilities

For interview math, the usual pieces are:

Bankers often exclude cash and debt from "operating" working capital. Say that if you get pushed. Definitions vary by firm and by model; clarity beats fake precision.

Why NWC matters in deals and DCFs

Growing companies often consume cash in AR and inventory even when they are profitable on an income statement. In a DCF, ΔNWC is a direct unlevered free cash flow line. In M&A, working capital pegs and true-ups show up in purchase agreements. In PE diligence, sudden NWC swings are a classic QoE / quality-of-cash topic.

The cash rule you should know cold

Increase in operating assets      → cash down
Increase in operating liabilities → cash up

On the cash flow statement (indirect method), you subtract an increase in NWC from CFO. That is the whole game.

Framework for every working capital prompt

1. What hit the income statement (if anything)?
2. Cash or non-cash / timing difference?
3. Cash flow statement adjustment
4. Balance sheet lines
5. Does it balance?
6. Say tax assumptions out loud

Drill 1: Inventory increases by $10 (cash purchase)

No sales yet.

Income statement: no change yet (inventory is a balance sheet asset until sold).
Cash flow statement: inventory up $10 → CFO −$10.
Balance sheet: inventory +$10, cash −$10. Still balances.

Inventory bought on credit

BS: inventory +$10, AP +$10. Cash unchanged at purchase.
Later when you pay: AP down $10, cash down $10.

When inventory is sold

Then COGS hits the income statement, inventory falls, and if sale is on credit AR rises. Do not jump ahead unless asked. Interviewers often isolate the purchase first.

Drill 2: Accounts receivable increase by $10

AR up means you booked revenue you have not collected. Relative to net income, cash is lower by the AR increase. On the CFS, increase in AR is a use of cash.

Full three statements with a credit sale of $10, tax 25%, ignore COGS

IS:  Revenue +10 → taxes +2.5 → NI +7.5
CFS: NI +7.5 − ΔAR 10 → cash −2.5
BS:  AR +10, cash −2.5, RE +7.5
Check: assets +7.5, equity +7.5. Balances.

Practice that until you do not need to peek. Then redo with COGS if they add inventory effects.

Drill 3: Accounts payable increase by $10

You received goods or services and have not paid yet.

Interview one-liner: rising payables means suppliers are financing operations. That helps near-term cash.

CFS: AP up → source of cash (+$10 in CFO).
BS: AP +$10, and either cash higher than otherwise or inventory/expense already recognized depending on scenario.

Always clarify whether the AP supports inventory (balance sheet only until sale) or an accrued expense already on the income statement.

Drill 4: Accrued expense increases by $10 (wage example)

Company incurs $10 of wage expense not yet paid. Tax 25%.

IS:  Expense +10 → NI −7.5
CFS: NI −7.5 + increase in accrued wages +10 → cash +2.5
BS:  Cash +2.5, accrued liability +10, RE −7.5
Check: assets +2.5 vs liabilities +10 and equity −7.5 → balances.

This is a frequent cousin of the depreciation question: expense hit NI, but cash has not left yet.

Drill 5: Deferred revenue increases by $10

Customer pays $10 cash before you deliver. Ignore tax for the pure case, or ask.

IS: no revenue yet
CFS: deferred revenue +10 → cash +10
BS: cash +10, deferred revenue +10

Later, when earned, revenue rises and deferred revenue falls. This is why SaaS / subscription businesses can show negative working capital dynamics.

Valuation tie-in

In a DCF:

UFCF = EBIT(1 − t) + D&A − CapEx − ΔNWC

If you forget ΔNWC, you overstate cash flow for firms that must fund growth in AR/inventory. Interviewers notice.

Qualitative prompts

"Can a company have rising NI and falling cash?"
Yes. AR and inventory growth, capex, debt paydown, dividends, etc.

"Is negative working capital good?"
Sometimes. If deferred revenue and payables structurally fund the business, it can be a cash advantage. It is not automatically good if it means the company is starving suppliers or delaying obligations unsustainably.

How to answer under time pressure

Use the fixed order every time. Narrate assumptions. If you make an arithmetic slip, the structure can still save you. If you have perfect arithmetic with no structure, one curveball ends you.

Student practice set (do these weekly)

1. Inventory +$10 cash purchase
2. Inventory +$10 on credit, then pay the AP later
3. AR +$10 with a credit sale (with tax)
4. AP +$10 with an accrued expense (with tax)
5. Prepaid expense +$10
6. Deferred revenue +$10
7. Combined: sell inventory on credit (inventory down, COGS up, AR up)
8. Explain ΔNWC in a DCF in 20 seconds

Then build a three-statement model and shock NWC. Watching the cash plug move teaches this faster than another article.

Connecting working capital to other interview topics

• Three statements linkage is the parent skill
• DCF free cash flow is where NWC becomes valuation
• M&A working capital pegs affect purchase price economics
• PE QoE asks whether earnings convert to cash

If you only memorize inventory/AR/AP in isolation, you will miss those bridges. Learn the drills, then say the "so what" for valuation and deals.