Why a Call Debit Spread and a Put Credit Spread Can Match at Expiration

Suppose a hypothetical stock is at $101. You pay $200 to open a call spread using the $100 and $105 strikes. Alternatively, you receive $300 to open a put spread using those same strikes. Despite the opposite opening cash flows, the two positions can have exactly the same profit or loss at expiration.

All four options have one shared future expiration and matching deliverables, with one standard U.S. equity-option contract in each leg. Each contract represents 100 shares, so a $1 per-share premium means $100 per contract. The premiums below are constructed hypothetical amounts, not live quotes, market estimates or calculator outputs. No particular remaining term is needed for this expiration payoff calculation. 1

The call debit spread buys the $100 call for $6 per share and sells the $105 call for $4. You pay $600 and receive $400, leaving a $200 net debit. This lower-strike purchase and higher-strike sale is also called a bull call spread. 2

The put credit spread sells the $105 put for $8 per share and buys the $100 put for $5. You receive $800 and pay $500, leaving a $300 net credit. This higher-strike sale and lower-strike purchase is also called a bull put spread. 3

“Debit” and “credit” describe money leaving or entering the account when the spread opens. They do not, by themselves, tell you how much the position can ultimately earn or lose. Receiving the $300 credit is not the same as having earned a $300 profit: the put spread still carries an obligation.

Follow the money to expiration

Start with an expiration stock price of $102.

The purchased $100 call has $2 per share of intrinsic value, while the sold $105 call has none. The call spread therefore has a $200 expiration value. That exactly offsets its $200 opening debit, so its profit is zero.

On the put side, the sold $105 put has $3 per share of intrinsic value against you, while the purchased $100 put has none. The put position has a net intrinsic-value liability of $300. That exactly offsets the $300 received at opening, so its profit is also zero.

The same accounting works across the entire range of expiration prices:

Stock price at expiration	Call spread: signed Position value	Put spread: signed Position value	Call spread P/L	Put spread P/L
$90	$0	−$500	−$200	−$200
$100	$0	−$500	−$200	−$200
$102	+$200	−$300	$0	$0
$105	+$500	$0	+$300	+$300
$110	+$500	$0	+$300	+$300

All amounts are total dollars for one complete spread. Signed Position value adds the long option’s intrinsic value and subtracts the short option’s intrinsic value, before accounting for entry. P/L also includes the opening premiums. The calculations exclude commissions and fees, financing, taxes, interim exercise/assignment cash flows and later share-position results.

At $100 or below, both calls have zero intrinsic value, so the call spread loses its $200 debit. The put spread instead has a $500 net liability, partly offset by its $300 opening credit. At $90, for example, the short $105 put contributes −$1,500 and the long $100 put contributes +$1,000. The remaining −$500, plus the original $300 receipt, gives the same $200 loss.

At $105 or above, the call spread’s intrinsic value reaches $500 and stops growing. Every additional dollar of value in the long call above $105 is offset by an additional dollar owed on the short call. Subtracting the $200 debit leaves a $300 profit. The put spread reaches that same profit differently: both puts have zero intrinsic value, leaving the original $300 credit.

Between the strikes, every $1 increase in the expiration stock price improves each spread’s result by $100. It increases the call spread’s asset value and reduces the put spread’s liability by the same amount.

The position values differ; the profits match

The two Position-value columns are not identical. The call spread’s signed expiration value is always $500 higher than the put spread’s.

But the opening positions also had different signed values. Using the hypothetical premiums, the call spread started at +$200, paid for with a $200 cash outflow. The put spread started at −$300, accompanied by a $300 cash inflow. The sign of the option position is the opposite of the opening cash flow.

Ignoring financing and costs, the accounting is:

\text{P/L}=\text{signed expiration Position value}-\text{signed entry value}

At a $102 expiration price, that gives:

\text{Call P/L}=\$200-\$200=0

\text{Put P/L}=-\$300-(-\$300)=0

The call spread’s $500 advantage in expiration position value is exactly offset by the $500 difference between their signed entry values. Matching P/L does not require matching unadjusted option values.

This gives the general condition for an exact match. Let $W=K_H-K_L$ be the strike width, $d$ the call spread’s debit per share and $c$ the put spread’s credit per share. For $q$ complete matching one-to-one spreads with multiplier $M$ , the difference in expiration P/L is:

\text{Call P/L}-\text{Put P/L}=qM(W-d-c)

The expression contains no expiration stock price: the difference is constant across the entire curve. Therefore, excluding financing and costs, the curves coincide when:

d+c=W

Here, $2+3=5$ , with $q=1$ and $M=100$ . Both spreads have a $300 maximum expiration profit, a $200 maximum expiration loss and a $102 expiration break-even. The call break-even is the lower strike plus the debit, $100+2=102$ ; the put break-even is the higher strike minus the credit, $105-3=102$ . These between-strike break-even formulas assume a positive debit or credit smaller than the width, as in this example. 2 3

If the debit and credit do not add up to the width, the matched spreads still have the same expiration shape, but one P/L curve sits above or below the other. The comparison requires the same underlying, strikes, expiration, quantities and deliverables, not merely two spreads that happen to be $5 wide. Scaling complete matching spreads multiplies the dollar results without changing the break-even price. Payoff and Break-Even covers the individual calculations in more detail.

Why interest changes the pricing comparison

The equality above is payoff arithmetic. It is not a rule that live premiums must always satisfy $d+c=W$ .

For European options, which can be exercised only at expiration, put-call parity relates calls and puts with the same underlying, strike and expiration. Under ideal financing and a continuous dividend yield, the per-share relationship is:

C(K)-P(K)=S_0e^{-aT}-Ke^{-rT}

Here, $C(K)$ and $P(K)$ are the call and put prices at strike $K$ , $S_0$ is the opening stock price, $a$ is the continuous dividend yield, $r$ is the continuously compounded annual interest rate and $T$ is the remaining time in years. 4 5

Subtracting the higher-strike relation from the lower-strike relation gives:

d+c=We^{-rT}

The common stock-and-dividend term cancels. The combined debit and credit equal the present value of the strike width, rather than necessarily the full width. Intuitively, the call position has an extra $500 of value at expiration; its extra economic cost today is the present value of that future $500.

For a separate hypothetical European comparison, use a $5 width, a 4% annual continuously compounded rate and 45 days, with $T=45/365.25$ :

5e^{-0.04(45/365.25)}\approx\$4.97542

With premiums satisfying that relation, subtracting opening premiums without accounting for interest leaves the call spread’s nominal expiration P/L about $2.46 higher per complete 100-share spread. That is the financing difference, not an unexplained payoff advantage.

Accounting for ideal financing at the same rate means carrying the opening debit forward as $de^{rT}$ and the credit as $ce^{rT}$ . The expiration P/L difference then becomes:

\text{Call P/L}_{\text{financed}}-\text{Put P/L}_{\text{financed}} =qM\bigl[W-(d+c)e^{rT}\bigr]=0

The last equality follows from the European pricing identity. Actual borrowing rates, interest earned on cash, collateral restrictions and execution costs need separate treatment. The Options Industry Council likewise describes the matching profiles as a comparison adjusted for carrying costs. 3 4

At a zero interest rate, the European identity reduces to $d+c=W$ . The main example was constructed to satisfy that undiscounted arithmetic; it makes no claim that current market interest rates are zero.

Where the similarity stops

American exercise rights and assignment

The standard U.S. equity options in the main example are American-style: they can be exercised before expiration. Their early-exercise rights mean strict European parity cannot simply be applied unchanged to their premiums. Dividends and the timing of strike payments can affect exercise decisions and actual values, despite the dividend cancellation in the ideal European vertical-spread identity. 1 4

The assignment obligations also differ. Assignment of the short $105 call requires delivery of 100 shares at $105. Assignment of the short $105 put requires purchasing 100 shares at $105, a $10,500 purchase. In each spread, the long $100 option remains a separate contract. Assignment of the short leg does not automatically exercise the long leg or resolve the whole position. 6

These options settle through shares, not by automatically exchanging the table’s net dollar amount in cash. The table does not determine which contracts are exercised or what shares remain afterward. A $200 maximum expiration loss therefore does not mean the account can never face a larger funding or share-delivery requirement. Later gains or losses on retained shares are outside that option-payoff limit. 1 6

Closing prices, capital and probability

Before expiration, closing either spread means selling its long option and buying back its short option. Both available transaction prices matter. A matching expiration curve does not guarantee identical interim marks or executable closing results after bid-ask spreads, costs, financing and American exercise effects. 2 3 The worked guide to debit spread value before expiration explains why being above both strikes does not establish an early closing value equal to the width.

Nor does the matching $200 expiration loss establish identical broker margin or buying-power requirements. The opening credit alone is not a measure of the capital needed to maintain or manage the position. Risk, Margin, and Assignment separates payoff limits from collateral and share funding.

In the constructed example, both spreads make an expiration profit only when the stock finishes above $102. Under the same assumed distribution of expiration prices, that is the same profit event. But the table does not say how likely it is or supply an expected-return estimate. There is no probability advantage inherent in the word “credit.”

Comparing the spreads in Options Calculator

In the options calculator, enter either spread separately on one underlying, with Entry price at $101, quantity 1 in each leg and the standard 100-share multiplier. Use the same future expiration, implied volatility, interest rate and dividend yield when comparing the two constructions. The calculator models American-style contracts and shares those inputs across the option legs.

For the expiration comparison, choose Profit / loss in the Stock price view and set Analysis date to expiration. Read the curve at different stock prices while keeping Entry price at $101. Profit / loss subtracts the signed model entry value; Position shows signed option value before that subtraction. As the table demonstrates, those vertical levels are not interchangeable.

The calculator recalculates opening premiums from Entry price, today’s date, implied volatility, interest rate and dividend yield. Editing opening assumptions changes that baseline; reading another price on the curve does not. There is no actual-fill input that locks in the constructed $6/$4 call premiums and $8/$5 put premiums, so entering these legs does not promise to reproduce this exact dollar table.

The model uses whole calendar days, with zero remaining model time on same-day expiration. It does not keep a financing cash-account ledger or include fees, taxes, broker margin, assignment-created shares or a discrete dividend schedule. It supplies neither live quotes nor an independent probability or expected-return estimate. See the calculator walkthrough for the controls and methodology for pricing, date and scope details.