Advanced Financial Management · Interest Rate Risk Management

Interest Rate Swaps for CA Final AFM

Updated 5 October 2026 · Fact-checked

An interest rate swap is an agreement where two parties exchange interest payments on a notional amount, usually fixed for floating, without swapping principal. To solve it, find each party's fixed and floating rate gap, compute the quality spread differential, split the gain, then write the net cash flows each period.

Understand Interest Rate Swaps

An interest rate swap is a contract between two parties to exchange interest payments on the same notional principal for a fixed period. The principal is never exchanged. It is only used to calculate the interest amounts.

The most common type is the plain vanilla swap. One party pays a fixed rate and receives a floating rate (such as MIBOR). The other party does the opposite. Payments are usually netted, so only the difference moves on each settlement date.

Why do firms swap? A firm may have a floating-rate loan but want certainty of cost. It pays fixed and receives floating under the swap, and its loan becomes effectively fixed. Another firm may expect rates to fall and want to move from fixed to floating. A swap does this without repaying the original loan.

Swaps also reduce cost through comparative advantage. A better-rated borrower usually pays less than a weaker borrower in both markets. But the gap is rarely the same. The quality spread differential (QSD) is the absolute difference between the two gaps. It is the total gain the two parties can share by borrowing where they each have the relative advantage and then swapping.

The original loans stay with the original lenders. The swap only changes the effective cost for each party. If a bank or dealer arranges the swap, its fee or spread is taken out of the total gain before the rest is shared.

Key rules to remember

Fixed-rate differential: Fixed differential = Fixed rate of weaker party − Fixed rate of stronger party; Use the rates each party would pay for direct borrowing.
Floating-rate differential: Floating differential = Floating spread of weaker party − Floating spread of stronger party; Compare spreads over the same benchmark, such as MIBOR.
Quality spread differential (QSD): QSD = |Fixed differential − Floating differential|; This is the absolute difference between the two differentials. It is the total gain available to share. If it is zero, there is no scope for a swap gain.
Comparative advantage rule: Stronger party borrows where the differential is wider; weaker party borrows where the differential is narrower; The stronger party borrows in the market where the differential is wider. The weaker party borrows in the market where the differential is narrower.
Net gain per party: Gain per party = (QSD − intermediary fee) ÷ 2 if shared equally; Share equally only if the question says so. Otherwise follow the stated ratio.
Net swap settlement: Net payment = Notional × (Fixed rate − Floating rate) × Period fraction; Positive means the fixed payer pays. Negative means the fixed payer receives.
Effective cost after swap: Effective cost = Rate on own loan + Swap payment rate − Swap receipt rate; Add what you pay and subtract what you receive. Do this for both parties and check the total.
Value of a swap to fixed payer: Value to fixed payer = PV of floating leg − PV of fixed leg; Value to the fixed receiver is the opposite. Just after a floating reset, the floating leg is worth the notional.

How to solve Interest Rate Swaps questions

Use this order for any swap question. It works for comparative advantage problems, cash flow problems and cost-comparison questions.

1List what each party can borrow at, in both fixed and floating markets, in a small table.
2Work out the fixed differential and the floating differential. Then compute QSD as the difference of the two.
3Identify who has the comparative advantage in which market. The market with the wider differential is where the stronger party borrows.
4Deduct any intermediary fee from the QSD. Share the balance as the question says (equal if silent).
5Decide the swap terms. Let each party's target net cost fix the rate it pays or receives to the other party. Pay or receive one leg at a floating benchmark and the other at a fixed rate.
6Write the net cost for each party by adding what it pays and subtracting what it receives. Compare with its cost without the swap.
7Check that the total saving equals QSD minus fees. Then convert rates into rupees using the notional and period.
8If cash flows are asked, compute each period's net settlement from the reset benchmark and state who pays whom.

Quickest way: Four-line QSD shortcut

When to use it: Use this when the question asks for gain, effective cost or swap terms from a table of fixed and floating rates for two companies.

Subtract the two fixed rates, then subtract the two floating spreads. QSD is the difference between these results.
Stronger party borrows in the market with the larger gap, and weaker party in the other.
Each party's target cost equals its own direct cost in the other market minus its share of the gain.
Back-solve the swap rate so that each party's net cost hits its target, then verify that total savings equal QSD less fees.

Common mistakes in Interest Rate Swaps

Treating the QSD as the gain of each party instead of the total gain.
Students stop after finding QSD and forget it must be shared.
Fix: Always write 'Total gain = QSD' and then divide it per the stated ratio after deducting any fee.
Letting each party borrow where its absolute rate is lower.
The stronger party is cheaper in both markets, so students pick the market that looks cheapest.
Fix: Compare the gaps, not the rates. The stronger party borrows where its advantage over the weaker party is larger.
Mixing a fixed rate with a floating spread when computing the differential.
Rates are quoted as 8% in one market and MIBOR + 1% in the other.
Fix: Compare fixed with fixed and spread with spread. Never subtract across the two markets.
Forgetting to add the rate on the party's own loan when stating effective cost.
Students focus on the swap legs alone.
Fix: Use the full formula: own loan + swap payment − swap receipt. Then check against the no-swap cost.
Treating the notional principal as an actual payment.
The word 'principal' suggests money moves.
Fix: Only interest is exchanged, and normally only the net amount. Principal is just the base for the calculation.
Ignoring the intermediary's fee or paying the fee in the wrong direction.
The fee is often stated at the end of the question.
Fix: Read the last line first. Deduct the fee from QSD before sharing, and recheck the total saving.

Worked examples

Example 1

Company A (higher rated) and Company B can borrow as follows. A: fixed 7%, floating MIBOR + 0.5%. B: fixed 9%, floating MIBOR + 1.5%. A wants a floating-rate loan and B wants a fixed-rate loan. Notional is ₹50,00,00,000 (₹50 crore). Without any intermediary, design a swap that shares the gain equally and state each party's annual saving in rupees.

Show the solution

Fixed differential = 9% − 7% = 2%. Floating differential = 1.5% − 0.5% = 1%.
QSD = 2% − 1% = 1%. This is the total gain. Each party gets 0.5%.
A's advantage is larger in the fixed market (2% against 1%). So A borrows fixed at 7%. B borrows floating at MIBOR + 1.5%.
Without the swap, A would pay MIBOR + 0.5%. With the 0.5% gain, its target cost is MIBOR.
Without the swap, B would pay 9%. With the 0.5% gain, its target cost is 8.5%.
Swap terms: A pays B a floating rate of MIBOR. B pays A a fixed rate of 7%.
A's net cost = 7% (to its lender) + MIBOR (to B) − 7% (from B) = MIBOR.
B's net cost = MIBOR + 1.5% (to its lender) + 7% (to A) − MIBOR (from A) = 8.5%.
Check: total cost with the swap = MIBOR + 8.5%. Total without = MIBOR + 0.5% + 9% = MIBOR + 9.5%. Saving = 1%, which equals QSD.
Annual saving for each = 0.5% × ₹50,00,00,000 = ₹25,00,000.

Answer: QSD is 1%. A borrows fixed at 7% and B borrows floating at MIBOR + 1.5%. A pays B MIBOR and B pays A 7%. A's net cost is MIBOR and B's is 8.5% fixed. Each saves 0.5%, which is ₹25,00,000 a year.

Example 2

XYZ Ltd has a ₹10,00,00,000 (₹10 crore) loan at MIBOR + 1% with annual interest. To fix its cost, it enters a 2-year plain vanilla swap with a bank as the fixed payer: it pays 8% fixed and receives MIBOR on the same notional. MIBOR set for year 1 is 7.5% and for year 2 is 9%. Find the net swap settlement and XYZ's total effective interest cost in each year.

Show the solution

Year 1 swap: XYZ pays 8% and receives 7.5%. Net payment = 0.5% × ₹10,00,00,000 = ₹5,00,000 paid by XYZ.
Year 1 loan interest = (7.5% + 1%) × ₹10,00,00,000 = 8.5% × ₹10,00,00,000 = ₹85,00,000.
Year 1 total cost = ₹85,00,000 + ₹5,00,000 = ₹90,00,000, which is 9%.
Year 2 swap: XYZ pays 8% and receives 9%. Net receipt = 1% × ₹10,00,00,000 = ₹10,00,000 received by XYZ.
Year 2 loan interest = (9% + 1%) × ₹10,00,00,000 = 10% × ₹10,00,00,000 = ₹1,00,00,000.
Year 2 total cost = ₹1,00,00,000 − ₹10,00,000 = ₹90,00,000, which is 9%.
Check by formula: effective cost = (MIBOR + 1%) + 8% − MIBOR = 9%, whatever MIBOR is.

Answer: Year 1: XYZ pays a net ₹5,00,000 on the swap. Year 2: XYZ receives a net ₹10,00,000. Its total interest cost is ₹90,00,000 in both years, an effective fixed rate of 9%.

Exam tips

Draw a small two-row table of fixed and floating rates for both parties before doing anything else. Most marks are lost by picking the wrong numbers.
Always show the check that total saving equals QSD less fees. Examiners give marks for reconciliation.
Read the question for who wants fixed and who wants floating, and the sharing ratio. These decide the swap terms.
State the swap terms in words (who pays whom, at what rate) and then show each party's net cost line by line.
In case-scenario MCQs, look for the net settlement. Compute (fixed − floating) × notional × period, and watch the direction of payment.

Practice questions from Interest Rate Risk Management

Interest Rate Swaps in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Interest Rate Swaps: frequently asked questions

How do I calculate the quality spread differential in a swap?

Find the difference between the two parties' fixed rates and the difference between their floating spreads. Take the absolute difference of these two gaps. The result is the QSD, which is the total gain available to share between the parties.

What is a plain vanilla interest rate swap?

It is the basic swap where one party pays a fixed rate and receives a floating rate on a notional amount, and the other party does the reverse. Only the net interest is usually paid, and principal never changes hands.

What is the difference between an interest rate swap and a currency swap?

An interest rate swap exchanges interest payments in the same currency, and the principal is not exchanged. A currency swap exchanges cash flows in two different currencies, and principal is normally exchanged at the start and returned at the end.

Who gets the gain if a bank arranges the swap?

The bank's fee or spread is taken out of the QSD first. The remaining gain is then shared between the two companies as the question states, equally if no ratio is given.

Does the swap change the original loan?

No. Each company keeps its loan with its own lender. The swap is a separate contract that changes only the effective interest cost the company bears.