> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ziplime.limex.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Costs & Commissions

> How trading costs are modeled in a backtest

Broker commissions are included in every backtest by default, so results are closer to what you'd actually see in live trading. You can also configure commissions in more detail for a specific scenario — for example, to match a particular broker's fee schedule.

Combined with the platform's [unified backtest / live logic](/language/introduction/engine-overview), this is meant to close the usual gap between "looks great in a backtest" and "holds up in live trading": the same cost model applies in both places, rather than costs being an afterthought bolted on to the results screen.

<Note>
  A realistic cost model reduces — but doesn't eliminate — the gap between backtest and live results. No backtest reproduces the future with full accuracy.
</Note>