Introduction
Post-only orders on Ethereum futures let traders place orders that never take liquidity, earning maker rebates while avoiding taker fees. Professional traders use this order type to capture fee discounts and improve execution quality on platforms like Binance Futures, CME, and Bybit.
Key Takeaways
Post-only orders guarantee maker status by executing only when matched against new orders. They prevent accidental liquidity-taking during order management. This order type suits market makers and directional traders prioritizing fee optimization over speed. Understanding the time-in-force rules prevents order rejections during low-liquidity periods.
What Is a Post-Only Order?
A post-only order is a limit order that only executes if it remains on the order book as a maker order. When you submit a post-only order, the system checks whether it would immediately match against existing orders. If a match would occur, the order gets rejected or adjusted rather than filled as a taker. This mechanism ensures the trader always pays maker fees, which are typically lower than taker fees. According to Investopedia, maker orders provide liquidity to exchanges and earn rebates, while taker orders remove liquidity and pay fees.
Why Post-Only Orders Matter
Post-only orders matter because fee structures directly impact trading profitability. On major Ethereum futures exchanges, maker fees range from 0.01% to 0.02%, while taker fees range from 0.03% to 0.05%. For high-frequency traders executing hundreds of positions daily, this difference compounds significantly. The BIS reports that fee arbitrage strategies account for substantial portions of algorithmic trading volume in crypto markets. Additionally, post-only orders prevent execution errors during fast-moving markets when traders accidentally market orders instead of limit orders.
How Post-Only Orders Work
Post-only order execution follows a specific logic flow: Step 1: Order Submission Trader submits a post-only limit order at a specified price level. Step 2: Matching Check System evaluates whether the order would immediately match against existing orders on the opposite side of the order book. Step 3: Execution Decision
- If no match exists → Order posts to book and awaits execution
- If match exists → Order gets rejected with “Post Only Would Match” error
Fee Calculation Model: Net Fee = (Maker Fee Rate × Position Value) – (Taker Fee Rate × Position Value) Example: $10,000 Ethereum futures position Maker fee (0.02%): $2.00 Taker fee (0.05%): $5.00 Savings per round trip: $6.00
Used in Practice
Professional Ethereum futures traders apply post-only orders in three primary scenarios. First, market makers use post-only orders to maintain bid-ask spreads while guaranteeing maker rebates. They post buy orders below current price and sell orders above, earning from the spread plus rebates. Second, arbitrage traders use post-only when capturing price discrepancies between spot and futures markets, ensuring they pay the lower maker rate. Third, swing traders use post-only to enter positions without accidentally paying higher taker fees when orders nearly match current prices.
Risks and Limitations
Post-only orders carry significant execution risks. During volatile Ethereum price movements, orders may sit unexecuted while the market moves against your position. This non-execution risk means traders miss entry or exit opportunities. Additionally, some exchanges apply time-in-force limits like good-till-cancelled or immediate-or-cancel, which interact with post-only functionality. The order book must have sufficient depth for post-only orders to fill, making them less suitable for illiquid contract months. Finally, sophisticated traders can detect post-only order patterns, potentially front-running your positions.
Post-Only Orders vs. Limit Orders vs. Market Orders
Understanding the distinction between these order types prevents execution mistakes. Post-only orders prioritize fee optimization. They guarantee maker status but may never execute if prices move away. They suit traders with time flexibility seeking lowest possible costs. Limit orders prioritize price but accept either maker or taker status depending on market conditions. If your limit price matches current prices, you become a taker and pay higher fees. They suit traders balancing price specificity with execution certainty. Market orders prioritize immediate execution above all else. They always execute as takers at current market prices, paying the highest fee rates. They suit traders requiring instant fills during time-critical situations.
What to Watch
Monitor order book depth when using post-only orders on Ethereum futures. Shallow order books increase non-execution probability, especially during off-peak hours. Watch for exchange-specific variations in post-only handling, as some platforms allow partial fills while others reject entirely. Track your actual fill rates when switching from standard limit orders, as post-only rejection rates can surprise unprepared traders. Finally, consider combining post-only orders with position sizing adjustments, since missing entries affects overall portfolio management.
Frequently Asked Questions
Can post-only orders guarantee execution?
No. Post-only orders only execute when your price does not match existing orders. If prices move away from your order, it remains unfilled until cancelled or the market returns to your level.
Do all Ethereum futures exchanges support post-only orders?
Most major exchanges including Binance Futures, CME, Bybit, and OKX support post-only orders. However, exact naming and implementation vary. Some exchanges call this “Post Only” while others label it “Maker Only” or “Post.”
What happens if my post-only order would immediately match?
The order gets rejected and returns an error message. Some exchanges offer a “post-only with allow-taker” option that switches to taker status if matching would occur, but this defeats the fee-saving purpose.
Can I use post-only orders for stop-loss exits?
Post-only orders are unsuitable for stop-loss exits because they require your price to sit above or below current market prices. Stop-loss orders need to trigger immediately when prices hit your level, requiring market or stop-limit order types.
How much can I save using post-only orders?
Savings depend on your trading volume and fee structure. For a trader paying 0.05% taker fees and 0.02% maker fees, each round trip saves 0.06%. On $100,000 monthly volume, this equals $600 in fee savings.
Do post-only orders work during market manipulation?
Post-only orders remain subject to market manipulation tactics like spoofing and layering. Sophisticated traders can detect your post-only orders and trigger false price movements to trigger your stops before prices reverse.
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