Post-only order
Also called: post only · maker-only order
Definition
A post-only order is a limit order that is only allowed to add liquidity to the order book; if it would fill immediately against an existing order, the exchange cancels or adjusts it instead.
This entry is shown in English.
How Post-only order works
A normal limit order placed at or across the best price fills straight away and pays the taker fee. Post-only prevents that. It guarantees that if your order executes, it does so as a maker, paying the lower maker fee or, at some fee tiers, earning a rebate.
This matters for active traders and market makers whose costs add up over many trades. It also protects you from accidentally crossing the spread when the price moves between setting your order and submitting it.
The trade-off is that your order may be rejected or never filled when the market is moving. Some exchanges simply cancel a post-only order that would take liquidity, while others reprice it to the best available maker price. Check your exchange's rules and fee schedule, as maker and taker fees differ by platform and VIP level.
Example
Suppose you trade 200,000 USDT of volume a month. If your exchange charges 0.02 percent maker and 0.05 percent taker on futures, all-taker trading costs 100 USDT a month while all-maker trading costs 40 USDT. Using post-only orders for most entries could save around 60 USDT a month, or 720 USDT a year, as long as you still get filled at the prices you want.
Common mistakes
- Being surprised when a post-only order is cancelled because it would have filled immediately.
- Using post-only when you urgently need to exit a position.
- Assuming maker fees are the same on every exchange or account tier.
Learn and practise
FAQ
Why was my post-only order cancelled?
Because at the moment it arrived, it would have matched an existing order and paid taker fees. The exchange cancelled it to keep it maker-only.
Does post-only guarantee maker fees?
Yes, if it fills, it fills as a maker. It does not guarantee that it will fill.
Is post-only the same as a limit order?
It is a type of limit order with an extra rule that it must not take liquidity.