Time-in-Force & Post-Only

Time-in-force decides what happens to unfilled quantity, while post-only prevents taker execution.

What it does

Time-in-force controls whether unfilled quantity waits, cancels, or prevents the order from executing at all. Post-only prevents a limit order from taking liquidity.

These are instructions applied to eligible orders, not separate markets.

How it works

Instruction	Immediate behavior	Unfilled quantity
GTC	Eligible quantity can fill	The remainder stays active until filled, canceled, or ended by another market or order lifecycle action
GTD	Eligible quantity can fill	The remainder stays active until filled, canceled, or its expiry
IOC	Eligible quantity fills immediately	The remainder is canceled
FOK	The complete quantity must fill immediately	The entire order is canceled if a full fill is unavailable
Post-only	A crossing order is rejected	No taker execution occurs

Post-only works with GTC and GTD limit orders. If you select post-only while IOC or FOK is set, the Order Form switches the order to GTC and tells you. Market execution is IOC-style rather than a resting time-in-force choice.

Set an expiry with GTD

Good Til Date (GTD) keeps a limit order active until the expiry you set. Choose Good Til Date under Time In Force in the Order Form, then choose Expires:

In 5 minutes, 30 minutes, 1 hour, 1 day, 7 days, or 30 days. A preset counts from the moment the order is placed.
Custom. A fixed date and time, between 1 minute and 30 days from now. If it passes while you are still reviewing the order, the Order Form asks you to choose a new one.

Quantity still open at the expiry is canceled, and the order shows as expired. Completed fills stay final. GTD is offered on Limit orders only, so the limit children of stop-loss and take-profit orders use GTC, IOC, or FOK.

When to use each instruction

Instruction	Use it when	Avoid it when
GTC	Unfilled quantity may wait for future liquidity	Any resting remainder would create unwanted exposure
GTD	Unfilled quantity may wait, but only until a chosen time	The order should stay active until you cancel it
IOC	Available quantity should fill now without leaving a remainder	The complete amount must fill or the order should do nothing
FOK	The complete amount must fill immediately or not at all	A partial fill would still be useful
Post-only	The order must add liquidity as a maker	Immediate execution matters or the price may cross the current market

A limit price by itself does not guarantee maker status.

Polyester rejects a post-only order that would cross the book. It does not reprice the order to keep it resting, and post-only cannot be combined with a market order.

FOK evaluates all executable liquidity within the order's price boundary after self-trade prevention. The visible Order Book can show only part of that liquidity, so its displayed rows are useful context but not the authoritative FOK test.

GTC has no maximum lifetime or hidden expiry. Pair disablement, delisting, cancellation, or another explicit lifecycle action can still end the order, but those events are not an expiry.

Available combinations depend on the Pair

The active Pair determines which instructions and combinations are available. A Pair in Post-Only mode, for example, accepts only post-only GTC and GTD orders.

Example

Let's say Bitcoin is currently trading at 100,000 USDT. You want to place a 0.01 BTC Limit buy at that price, but only 0.006 BTC is available immediately. You choose the instruction based on whether a partial fill is useful, whether the remainder can wait, or whether the entire order must fill at once. You choose post-only when your goal is to add liquidity instead of executing immediately.

Here is what each instruction does:

GTC can fill 0.006 BTC and leave the remaining 0.004 BTC open on the Order Book.
GTD can fill 0.006 BTC and leave the remaining 0.004 BTC open until your expiry, then cancel whatever is still open.
IOC can fill 0.006 BTC and cancel the remaining 0.004 BTC.
FOK cancels the entire order because the full 0.01 BTC cannot fill immediately.
Post-only rejects the order if its 100,000 USDT limit price would immediately match a resting ask.

Result: The price and quantity stay the same, but the instruction changes what happens to the order and any unfilled quantity.

These are example prices and available quantities. FOK evaluates all eligible liquidity, which can differ from the rows currently visible in the Order Book.

What to watch

Maker or taker treatment is determined per fill.
A partially resting order can have both immediate and later fills when post-only is not used.
Self-trade prevention can end an otherwise eligible match.
A post-only rejection means the submitted price would have removed liquidity at admission.

Market Order Attempt immediate execution against available Order Book liquidity within price protection. Limit Order Buy at a chosen maximum price or sell at a chosen minimum price. Iceberg Understand the Iceberg order concept and its current availability on Polyester. TWAP Spread a target quantity across scheduled child orders while monitoring execution, timing, and completion risk. Ladder Distribute a target quantity across planned limit-price levels and monitor each child order independently. Stop Loss Market Attempt market-style execution after a downside condition while accounting for gaps, protection, and partial fills. Stop Loss Limit Activate a limit child after a downside condition while keeping trigger price and execution boundary distinct. Take Profit Market Attempt market-style execution after the price reaches your profit target, while accounting for gaps, protection, and partial fills. Take Profit Limit Place a limit child when the price reaches your profit target, keeping the trigger price and execution boundary distinct. Trailing Stop Follow a favorable price extreme and activate a child order after price reverses by a configured distance.