How to Use Fill or Kill Orders on MT5

Fill or Kill, often abbreviated to FOK, is one of three order fill policies available on MetaTrader 5. It tells the platform to either fill your order in full at the specified price or cancel it entirely. Partial fills are not allowed under this policy.

This article explains what Fill or Kill means in practice, how it differs from the Immediate or Cancel and Return fill policies, how to set FOK when placing an order, and when this policy is useful compared with the alternatives.

What Is Fill or Kill on MT5?

The fill policy of an order tells the platform how to handle a situation where the requested volume cannot be fully matched at the price you specified. Fill or Kill is the strictest of the three policies on MT5: either the entire order is filled at the requested price, or the order is cancelled. No partial execution occurs.

If you place a 5-lot order with Fill or Kill and only 3 lots are available at your specified price, the order is cancelled in full. You receive no execution rather than a partial fill of 3 lots.

This is also the only fill policy available on MetaTrader 4. On MT5, you have the choice between Fill or Kill, Immediate or Cancel, and Return.

How Fill or Kill Differs from Immediate or Cancel and Return

The three fill policies on MT5 behave differently when full volume is not available at the requested price.

Fill or Kill: All or nothing. Either fill the entire order at the requested price or cancel completely.

Immediate or Cancel (IOC): Fill what is available at the requested price immediately. Cancel any unfilled portion. Partial fills are accepted. Using the example above, a 5-lot IOC order would fill 3 lots and cancel the remaining 2 lots.

Return: Fill what is available at the requested price. Any unfilled portion stays active and continues to seek execution. Partial fills are accepted but the remainder is not cancelled. Using the same example, a 5-lot Return order would fill 3 lots immediately, with the remaining 2 lots staying active.

The key distinction is what happens to the unfilled portion: Fill or Kill cancels everything, Immediate or Cancel cancels only the unfilled portion, and Return keeps the unfilled portion active.

How to Set Fill or Kill on MT5

Fill or Kill is selected at the time of order placement.

Open the New Order dialog. You can do this in several ways: press F9, click Tools > New Order, click the New Order button on the toolbar, or right-click a symbol in Market Watch and select New Order.

In the New Order dialog, select the symbol, set the volume, and configure the order type (market or pending). The Filling dropdown shows the available fill policies for that symbol. Select "Fill or Kill" from the dropdown.

Configure any additional fields such as Stop Loss, Take Profit, and expiry (for pending orders), then click Place (for pending orders) or Buy / Sell (for market orders).

The fill policy applies to that specific order only. Each new order can have its own fill policy selected.

When Fill or Kill Is Useful

Fill or Kill is useful when you do not want a partial fill under any circumstances. This typically applies in two situations.

The first is for strategies that depend on a specific total position size. If your risk management or strategy requires entering a position of exactly 5 lots, a partial fill of 3 lots would leave you under-positioned and require additional action to either complete the position at a possibly worse price or close the partial position.

The second is for traders who want clear go / no-go execution at a specific price. With FOK, you either get the position you wanted at the price you wanted, or you do not enter at all. This removes the ambiguity of partial execution.

For most retail forex trading on smaller lot sizes, full execution at the requested price is the norm, and the difference between the three fill policies is often invisible. The choice becomes more material as lot size increases and as liquidity at the requested price level becomes a binding constraint.

When Fill or Kill May Not Be the Best Choice

Fill or Kill is the most restrictive policy. There are situations where one of the other policies fits better.

If you would prefer to enter with a smaller position rather than miss the trade entirely, Immediate or Cancel allows partial fills. You take what is available at your price, and the rest is cancelled. You are in the market, just at a reduced size.

If you want to leave the unfilled portion working to enter at the same price as liquidity returns, the Return policy keeps the remaining volume active. You get what is available immediately, and the rest continues to seek execution.

In low-liquidity conditions or for larger volumes, FOK orders may be cancelled more often than they fill, particularly if the requested price is at a level with limited volume available.

Symbol-Level Availability of Fill Policies

The fill policies available for a specific symbol depend on the broker's symbol-level configuration. Not every symbol on MT5 supports every fill policy. When you open the New Order dialog for a particular symbol, the Filling dropdown will show only the policies enabled for that symbol.

If a fill policy you want is not available for a specific symbol, the option will simply not appear in the dropdown. The available policies vary by instrument and are set at the broker level.

Practical Considerations

Fill or Kill is the strictest fill policy. For most retail traders on standard lot sizes, the difference between FOK, IOC, and Return is often negligible because full execution is typically achievable at the requested price.

The choice of fill policy becomes more significant as trade volume increases relative to available liquidity at the requested price. For very large lot sizes or during low-liquidity conditions (such as around market open or close, or during high-impact news events), a FOK order is more likely to be cancelled than filled.

Orders are executed at the best available market price, which may result in positive or negative slippage. Demo accounts often execute instantly and may not fully replicate live slippage conditions. The behaviour of fill policies on demo accounts may differ from live accounts.

The fill policy applies to the moment of order placement or pending order trigger. Once a position is open, the fill policy no longer applies; you simply have an open position that can be managed normally.

Trading at TIOmarkets

TIOmarkets offers MetaTrader 5 and MetaTrader 4 on desktop, web, and mobile, across four account types. The Standard account is created automatically on registration with a minimum deposit of $20 or currency equivalent. The Raw and VIP Black accounts are opened separately through the client area. The Nano account is MT5 only with a $20 minimum deposit, USD only. Hedging is supported on all accounts. A swap-free Islamic account is available; contact TIOmarkets for eligibility and instrument requirements. Copy trading is available on both MT4 and MT5.

Orders are executed at the best available market price, which may result in positive or negative slippage. Demo accounts often execute instantly and may not fully replicate live slippage conditions. Spreads are variable and are typically higher than minimum figures shown. Leverage on each instrument is subject to change depending on market conditions and applicable regulatory requirements. You can review the full list of account types on the TIOmarkets accounts page.