Credit spreads vs debit spreads. When to use which.
Credit spreads and debit spreads are the two most common defined risk options structures. They look similar on the order ticket. Two strikes, same expiry, one bought and one sold. The only mechanical difference is whether the trader pays premium (debit) or collects premium (credit) at entry. The behavioral and mathematical differences after entry are large enough that picking the wrong one for the environment is one of the most common retail options mistakes.
The honest version of which to use is not a preference question. It is an IV rank question, combined with a directional conviction question and a probability of profit question.
What a credit spread is
A credit spread sells a closer to the money option and buys a further out of the money option of the same type and expiry. The premium collected on the sold option is more than the premium paid on the bought option. The trader collects a net credit at entry.
The two common bullish to neutral structures:
Bull put spread. Sell a put at strike A. Buy a put at strike B, below A. Both same expiry. The position profits if the stock stays above strike A. Maximum profit is the credit collected. Maximum loss is the spread width (A minus B) minus the credit.
Bear call spread. Sell a call at strike A. Buy a call at strike B, above A. Both same expiry. The position profits if the stock stays below strike A. Maximum profit is the credit collected. Maximum loss is the spread width (B minus A) minus the credit.
The credit spread's profit math is asymmetric. Win small, often. Lose large, sometimes. The risk reward on a 30 delta short strike is typically about 1 to 3 (collect $1 to risk $3), and the probability of profit is around 70 percent. The math works because the small frequent wins compound when sized correctly.
What a debit spread is
A debit spread buys a closer to the money option and sells a further out of the money option of the same type and expiry. The premium paid on the bought option is more than the premium collected on the sold option. The trader pays a net debit at entry.
The two common directional structures:
Bull call spread. Buy a call at strike A. Sell a call at strike B, above A. Both same expiry. The position profits if the stock moves up through A and toward B. Maximum profit is the spread width (B minus A) minus the debit. Maximum loss is the debit paid.
Bear put spread. Buy a put at strike A. Sell a put at strike B, below A. Both same expiry. The position profits if the stock moves down through A and toward B. Maximum profit is the spread width (A minus B) minus the debit. Maximum loss is the debit paid.
The debit spread's profit math is closer to symmetric. The risk reward on an at the money long strike with a target one strike width away is typically about 1 to 1 or 1 to 2 (pay $1 to make $1 or $2), and the probability of profit is around 40 to 50 percent. The math works when the trader is right on direction more often than the implied probability.
The IV rank rule
The single biggest decision factor is IV rank. High IV rank favors credit spreads. Low IV rank favors debit spreads.
IV rank above 50: credit spreads. The premium collected is rich relative to history. The IV is likely to revert lower over time, which adds tailwind to the short premium position. Time decay also helps. The structure has two tailwinds (time decay and IV mean reversion).
IV rank below 30: debit spreads. The premium paid is cheap relative to history. The IV is likely to revert higher over time, which adds tailwind to the long premium position. Time decay still hurts, but the IV expansion can offset enough of the theta to make the structure work. The structure has one tailwind (IV mean reversion) and one headwind (time decay).
IV rank 30 to 50: no IV edge. The structure choice comes from probability of profit preference and directional conviction strength. If the trader wants high probability with smaller wins and larger occasional losses, credit. If the trader wants lower probability with capped losses and target reaching wins, debit.
The directional conviction question
Beyond IV rank, the trader's level of conviction on direction and magnitude matters.
Low to medium directional conviction, just want price to stay away from a level. Credit spread. Sell premium below the level (bull put) for an upside bias, or sell premium above the level (bear call) for a downside bias. The trade does not need a big move. It needs the stock to stay on the right side of the short strike.
High directional conviction, want to capture the move. Debit spread. Buy premium at or slightly in the money, sell premium at the target price. The trade needs the stock to reach the target by expiry. The directional thesis has to be strong enough to overcome the probability of profit math.
This decision rule combines with the IV rank decision rule.
High IV plus low conviction: credit spread far out of the money.
High IV plus high conviction: credit spread closer to the money, or sometimes a debit spread if the IV crush after the catalyst is expected to be smaller than the directional move.
Low IV plus high conviction: debit spread, possibly closer to the money or longer dated.
Low IV plus low conviction: probably do not take the trade. Without IV tailwind or strong directional conviction, there is no edge to express.
The risk reward shapes compared
Credit spread on SPY example. SPY at $500. Sell the $490 put for $2 credit. Buy the $485 put for $1. Net credit $1. Spread width $5. Max profit $1 ($100 per contract). Max loss $4 ($400 per contract). Risk reward 1 to 4. Breakeven $489 ($490 short minus $1 credit). Probability of profit roughly 75 percent.
Debit spread on SPY example. SPY at $500. Buy the $500 call for $5 debit. Sell the $510 call for $3 credit. Net debit $2. Spread width $10. Max profit $8 ($800 per contract). Max loss $2 ($200 per contract). Risk reward 4 to 1. Breakeven $502. Probability of profit roughly 40 percent.
The credit spread wins more often, each win is smaller, occasional losses are larger. The debit spread wins less often, each win is larger, losses are capped at the debit. Different distributions of the same expected value when both are correctly priced.
The strike selection rules of thumb
Credit spread strike selection
Short strike at a delta of 0.20 to 0.30 for high probability setups. Short strike at 0.30 to 0.40 for higher premium income setups with lower probability. The long strike is typically one strike width further out (one strike on broad indexes, sometimes two on stocks with denser strikes).
The expiry is typically 30 to 45 days to expiration (DTE) for the cleanest theta to gamma ratio. Closer to expiry has higher gamma risk (the short strike can blow through quickly on a bad move). Further from expiry has more theta to wait out.
Debit spread strike selection
Long strike at the money or one strike in the money, so price has less distance to cover to reach the short strike. Short strike at the target price level.
The expiry is typically 45 to 60 DTE so there is time for the move to develop and IV to expand. Buying short dated debit spreads is a high theta drag bet. Longer expiry gives the directional thesis time to play out.
The management rules
Credit spread management
Close at 50 percent of max profit on broad indexes, 25 to 50 percent on stocks. Do not let the position run to expiry hoping for full profit. The risk reward of the last 25 percent of profit is terrible.
Manage the loss side at twice the credit collected. Spread collecting $1 of credit, close if loss reaches $2 (not the max loss of the spread width minus credit). This caps the worst case and avoids the asymmetric loss that wipes out months of small wins.
Debit spread management
Close at the target if the spread reaches it before expiry. If direction is right, a debit spread often gets most of the way to max profit before expiry. Capturing that is better than holding for the last piece and risking time decay if the move stalls.
Cut the loss at 50 percent of the debit paid if direction is clearly wrong. The asymmetry of the debit spread means a partial loss now is better than waiting for expiry to potentially recover.
Where the audit fits
The audit does not check IV rank or pick a structure for you. If spreads are your setup, the setup chapter lifts your description of when you buy them and when you sell them, in your words. Your max risk is the number you gave me, and your stop and exit are written as you described them. The Historical Audit splits your options results by calls and puts and by days to expiry. Twelve chapters, several thousand words, on a private URL that stays yours.