Order execution
Why a post-only order can disappear without a fill
At a glance
On Bybit, post-only cancels an order that would execute immediately instead of resting in the book. This enforces maker-only behavior; it does not guarantee that the order will trade or that waiting improves the final price.
On this page
A cancellation message is not always an execution error. A post-only instruction can deliberately prevent a fill that an ordinary limit order would allow. The useful question is whether the order reached the book as a resting order or would have matched immediately.
The constraint you selected
Bybit's post-only documentation says it cancels an order if immediate execution would occur. Treat that as a platform-specific rule and check the current product instructions. Maker classification itself is not a promise of a zero fee or a rebate.
Consider this fictional sequence for a one-unit buy:
| Moment | Best ask | Your limit |
|---|---|---|
| You inspect the book | 25.10 USDT | Not submitted |
| You submit the order | 25.10 USDT | 25.00 USDT |
| The order arrives | 24.95 USDT | 25.00 USDT |
The limit has not changed, but the available ask has. At arrival, 24.95 is below your maximum purchase price of 25.00. Ordinary immediate matching would satisfy the price constraint. Post-only introduces a second constraint: do not take available liquidity. Cancellation can therefore be the correct outcome.
A cheaper fee is only one variable
Use illustrative fees, not a claimed exchange schedule: buying 100 USDT of an asset at a hypothetical 0.02% maker rate costs 0.02 USDT; at a hypothetical 0.05% taker rate it costs 0.05 USDT. The difference is 0.03 USDT. If a later purchase of the same quantity costs 0.20 USDT more before fees, that movement outweighs the original fee difference.
This arithmetic does not predict which method is cheaper. It explains why a fee comparison alone cannot settle the execution decision. Conversely, a patient order might obtain a favorable price or never execute at all.
Investigate before repeating
Check the cancellation reason, the order's arrival time and whether any fill exists. A screenshot of the book taken earlier is not proof of liquidity when the matching engine evaluated the order. Avoid repeatedly increasing the limit just to make the order appear accepted: that changes the price constraint you chose.
If your priority is maker-only execution, a canceled order may respect that priority. If your priority is immediate execution, recognize the conflict instead of treating both as guaranteed. See partial fills and time in force for the separate question of what happens to a remainder.
CoinFom editorial note: research, writing, translation and review used AI assistance. No live transaction was performed for this article. Numerical examples are hypothetical and do not demonstrate returns. Sources checked September 26–27, 2026. Educational content, not personalized advice. See About CoinFom, our editorial and affiliate policy, or send a correction. CoinFom may earn referral commissions on other pages; this article contains no signup link.