How to Use "Post-Only" Orders to Ensure You Are a Market Maker?

Understanding Post-Only Order Mechanics

1. A post-only order is a type of limit order that executes exclusively as a maker—never as a taker.

2. If the order would immediately match with an existing order on the opposite side of the order book, the exchange rejects it instead of filling it.

3. This behavior enforces placement only at prices that do not cross the spread, thereby adding liquidity to the market.

4. Exchanges like Binance, Bybit, and OKX enforce this rule strictly, often returning error codes such as 'PostOnlyOrderWouldMatch' when violated.

5. The order remains in the order book until another trader’s incoming market or aggressive limit order matches against it.

Strategic Placement for Optimal Liquidity Provision

1. Traders must place post-only orders beyond the best bid or ask—typically one tick away from the current top-of-book price.

2. On BTC/USDT markets with 0.1 USDT tick size, placing a buy at $61,420.0 when the best ask is $61,420.1 satisfies the condition.

3. Aggressive pricing—such as matching or crossing the spread—triggers automatic cancellation without execution.

4. Some platforms allow setting post-only via API flags like postOnly=true or order types like limit_post_only.

5. Manual traders on web interfaces often enable a checkbox labeled “Post-only” before submission, which internally applies the same logic.

Risk Mitigation Through Conditional Execution

1. Post-only orders eliminate slippage risk inherent in market orders, preserving intended entry or exit levels.

2. They prevent accidental taker status during volatile spikes where bid-ask spreads widen rapidly.

3. During flash crashes or pump-and-dump events, these orders avoid being swept by predatory liquidity-taking algorithms.

4. Arbitrageurs rely on post-only to maintain clean maker status across multiple venues while quoting tight spreads.

5. Rejection feedback serves as real-time confirmation that the order contributes to depth rather than consuming it.

Fees and Incentives for Consistent Market Making

1. Most exchanges apply negative maker fees—or rebates—for orders that add liquidity, ranging from -0.01% to -0.025% per executed volume.

2. Taker fees are significantly higher, often between 0.04% and 0.1%, creating strong economic incentive to remain a maker.

3. Volume-based fee tiers reward high-frequency post-only activity with deeper rebate schedules.

4. Certain derivatives platforms offer additional incentives such as trading competition points or token airdrops tied specifically to verified maker volume.

5. Loss of maker status—even once—can delay progression through fee tiers, affecting long-term cost structures.

Frequently Asked Questions

Q: Can a post-only order be canceled manually after submission?Yes. Once placed and resting in the order book, it behaves like any other limit order and supports standard cancel operations via API or UI.

Q: Does time-in-force affect post-only behavior?No. GTC (Good-Til-Canceled), IOC (Immediate-Or-Cancel), and FOK (Fill-Or-Kill) modifiers operate independently of post-only logic. However, IOC and FOK are incompatible with post-only because they imply immediate execution intent.

Q: What happens if network latency causes a race condition where my post-only order arrives just after a price shift?The exchange evaluates the order against the live order book state at arrival time. If it no longer meets post-only criteria due to recent fills or cancellations, it gets rejected.

Q: Do stop-limit orders support post-only mode?Generally no. Stop-limit orders activate only after a trigger price is met, and their limit component cannot guarantee maker status upon activation. Most exchanges disable post-only for stop-based order types.