Limit orders, maker fees and post-only: what each setting controls

A limit price does not assign the fee role

A buy limit expresses the highest acceptable purchase price; a sell limit expresses the lowest acceptable sale price. It does not promise that the order will wait. If a compatible opposite order already exists, a limit order can match immediately. Kraken's pricing guide explains that a marketable limit can incur a taker fee. The practical question is therefore not whether you typed a price, but whether your order added liquidity or consumed it when the execution happened.

Understand the post-only condition

Post-only adds an execution constraint. Bybit documents that an order which would immediately take liquidity is canceled rather than allowed to fill as a taker. This can preserve the maker condition, but it cannot promise execution, a particular waiting time or a favorable eventual price. Availability and exact behavior depend on the product. Read the order acknowledgment as well as the setting itself: an order rejected by this constraint is not a resting order waiting for a later match.

Use a small order-book example

Suppose the best bid is 100 USD and the best ask is 101 USD. A normal buy limit at 102 USD permits matching with the available 101 USD sell order; the fact that 102 was entered does not require the exchange to charge 102. A post-only buy submitted with that same marketable price would not be allowed to take that liquidity under the described rule. A buy limit below the ask might instead rest, provided conditions have not changed before acceptance.

Track partial fills and remaining quantity

A normal limit order can consume some available quantity and leave a remainder, depending on its price and validity instructions. Review filled quantity and remaining quantity separately. If an original ten-unit order fills four units, an open remainder of six does not mean you still have a ten-unit request outstanding. Before replacing an order, verify whether cancellation succeeded and whether another fill arrived during the request. This operational check helps prevent an accidental duplicate order from being confused with a fee discrepancy.

Compare the condition with your actual objective

Post-only is a tool for controlling liquidity-taking behavior, not a universal answer to execution decisions. A resting order can remain unfilled while conditions change. Repeatedly moving a limit simply to obtain a maker label can change the final price more than the commission difference. In a hypothetical example, a 0.30 USD fee reduction does not offset a 2 USD worse purchase price for the same quantity. Evaluate the completed price and fee together instead of scoring the order by its label.

Read the final record, not just the preview

Keep the submitted limit, post-only setting, accepted order status, execution timestamps and final liquidity role. When investigating an unexpected fee, locate the specific fill and compare its charged rate with the applicable account schedule. The estimated fee shown before submission is not a substitute for the final ledger. A canceled order with no fill should not be treated as a completed trade in a cashback estimate. Any eligible reward still depends on the actual partner commission record and account attribution.