Why a Post-Only Order Was Rejected or Cancelled
Read post-only as a matching constraint, recognize venue-specific reject or cancel outcomes, and keep the observed maker/taker evidence separate.
Distinguish a limit price from a post-only constraint
A limit order can take liquidity when its price crosses the opposing side of the book. Adding a post-only constraint changes which immediate matching behavior is acceptable. This helps explain why an order intended to rest disappears at placement. Begin with the exact order type or setting recorded by the venue; an ordinary limit label is not enough to establish post-only behavior.
Read crossing behavior using a simple book example
Use a saved book observation to understand the direction of a possible cross. A buy limit at an observed best ask can immediately meet opposing liquidity in the hypothetical example. The constraint then produces the documented venue outcome. Keep the observation time because the market can change between seeing a price and the venue handling an order; a later screenshot cannot recreate that moment.
Keep Binance rejection and Bybit cancellation distinct
The response vocabulary matters. Binance documents rejection for its crossing LIMIT_MAKER order, while Bybit documents cancellation for PostOnly in the described situation. Coinbase documents its own whole-order rejection rule. Record the original response or final status with its venue and product. A single universal label would remove precisely the distinction this checklist is meant to preserve.
Separate resting eligibility from later execution
Qualifying to rest and receiving a later maker execution are separate questions. A resting order may remain unfilled, and a fee record may describe the role attached to an actual fill. Keep placement evidence apart from any execution and its liquidity classification. The worksheet explains the matching constraint; it does not estimate commissions or promise a particular rate or execution outcome.
Record the placement and execution evidence
Use the CSV to connect the selected setting, recorded limit price, observed opposing price and actual response. If one part is unavailable, leave it unknown rather than choosing an explanation from the price alone. The TXT checklist provides a shorter review. Both downloads are blank and can be used with existing records without submitting another order or connecting an account.
Documented venue distinctions
These statements apply to the named provider and documented product. They do not imply identical rules elsewhere.
- Binance Spot LIMIT_MAKER rejects an order that would immediately take liquidity. Official reference.
- Bybit PostOnly cancels an immediately executable order, including documented placement-time market changes. Official reference.
- Coinbase Exchange rejects the whole post-only order if any portion would take liquidity. Official reference.
Hypothetical case
Hypothetical best ask: 100. A post-only buy limit at 100 would take the displayed liquidity and receives the venue-defined reject or cancel outcome. A limit at 99.9 can qualify to rest, but changing prices and other checks still matter.
Six questions for your record
- What exact post-only field or type was selected?
- Which venue rule describes that field?
- Was an immediately crossing price recorded?
- What response or final status is confirmed?
- Did any own fill occur?
- Was the actual liquidity role recorded for that fill?
Keep your own record
The CSV contains column headings only. The TXT contains the review questions and blank note spaces. Keep original evidence separately, preserve identifiers as text and leave missing facts unknown. Neither file sends data or performs an account check.