What Is a Post-Only Order in Crypto? The Venue Rules
A post-only order rests on the book as a maker or does not trade. What Coinbase, Kraken and Gemini documents say, plus a worked maker-taker cost.
A post-only order in crypto is a limit order with one extra condition: it may only enter the order book as a resting maker order. If its price would trade immediately against an existing order, the venue will not let it fill as a taker. Depending on the venue, it is rejected or repriced. The point is fee control.
This is an evergreen explainer; this desk read the venue documents below on 18 October 2026, and operators rewrite them.
What is a post-only order in crypto, and why does it exist?
The maker’s order was resting on the book; the taker’s arrived and matched it. Exchanges price the two sides differently.
A plain limit order sets a price. It does not set the fee. Send a buy limit at or above the best ask and it matches on arrival, pays the taker rate, and any remainder rests. Post-only closes that gap. The instruction is maker or nothing.
A price can look passive on screen and still cross by the time it reaches the matching engine, because the book moves in between. That is the case the flag exists for.
What happens if a post-only order would cross the spread?
It depends on the venue.
| Venue | Where the setting lives | What the page read says on a cross |
|---|---|---|
| Coinbase Advanced | “Post only” execution option on a limit order | Whole order rejected if any part would execute on arrival |
| Kraken | post in the AddOrder oflags parameter, limit orders only | Not stated in the API reference read |
| Gemini ActiveTrader | Fee schedule read; order-handling page not read | Not covered here |
| Crypto.com Exchange | Help article titled Smart Post-Only Orders | Article text did not open for this desk |
Coinbase’s help page on Advanced order types is the most explicit. Post only keeps a limit order on the book to be charged maker fees if filled; if any part would execute immediately on arrival, the entire order is rejected. The alternative is Allow Taker, which lets the order execute even if it crosses the spread, with the crossing portion charged at the taker rate. Coinbase also says its TP/SL orders can only execute with the Allow Taker flag.
Kraken’s AddOrder reference lists post as a post-only order flag, available when the order type is limit. The text read does not say whether a crossing order is rejected or cancelled, and this post does not guess.
What does a post-only order save? A worked cost on Gemini’s ladder
Coinbase’s public fees help page prints no rates; it tells the reader to sign in to see them, so no Coinbase figure runs here. Gemini publishes its ActiveTrader Fee Schedule, dated September 1, 2026, so the arithmetic uses Gemini’s numbers.
| Gemini ActiveTrader spot tier | Maker | Taker | $10,000 fill as maker | As taker |
|---|---|---|---|---|
| Base (≥ $0) | 0.600% | 1.200% | $60 | $120 |
| $10K volume or $1M balance | 0.400% | 0.800% | $40 | $80 |
At both tiers the taker fill costs twice the maker fill. Per the schedule, the tier follows whichever of trailing 30-day volume and asset balance earns the lower fee, recalculated daily at about 2am UTC. A partially matched order pays taker on the part that matched immediately and maker on the rest, and cancelling a resting maker order costs nothing.
That is the trade post-only makes: certainty of the maker rate, no certainty of a fill. The full ladder is in our Gemini ActiveTrader fee schedule review; see also the Coinbase Advanced review and the Gemini vs Kraken Pro tier comparison.
Post-only vs limit order vs smart post-only
A standard limit order fills at its price or better and takes if it crosses. Post-only adds the refusal to take. Smart post-only, a variant some venues offer, reprices the order to a level where it rests instead of refusing it.
Post-only order FAQ
Does a post-only order guarantee maker fees?
On Coinbase Advanced, the help page says post only keeps the order on the book to be charged maker fees if filled, and rejects the whole order otherwise. So it guarantees the fee class of any fill, not a fill. The maker rate itself is whatever the schedule says: Coinbase applies the tier you hold at the time of the order.
Can market orders be post-only?
No. A market order executes against resting orders on arrival, which is the definition of taking. Coinbase’s order-types page says market orders are always taker orders, and Kraken’s AddOrder reference makes the post flag available only when the order type is limit. Post-only is a condition on a limit order; on a market order it has nothing to attach to.
What is the difference between standard and smart post-only?
Standard post-only refuses to take: if the order would cross, it does not trade, and Coinbase, for one, rejects the whole order. Smart post-only is a variant some venues offer that reprices the order to a level where it rests instead of refusing it. The first protects the price you typed; the second protects the order. Read the venue’s own rule before using either.
Can a post-only order be combined with IOC?
They pull in opposite directions. Immediate-or-cancel, as Kraken’s reference defines it, executes what it can at once and cancels the rest rather than resting; post-only forbids executing at once. On Kraken the two sit in separate parameters, oflags and timeinforce, and the reference read does not say how the engine treats both together. Check the venue’s documentation before sending real size.
An order flag is plumbing, not a strategy, and nothing here says what to trade or when. Crypto assets are high risk. Venue rules change quietly; read the operator’s current page before relying on any line here.