Margin Requirement for a short Iron Condor

You must have a margin account to trade an iron condor

The buying power effect for a short iron condor is the requirement of the short credit spread on one side of the position if both sides are the same width.  However, If not, then the buying power requirement will use the wider side.

Example of selling an iron condor in a margin account

Buy to open 2 MAR 50 puts at $0.80

Sell to open 2 MAR 53 puts at $1.25
Sell to open 2 MAR 67 calls at $2.00

Buy to open 2 MAR 70 calls at $0.75

The margin requirement for this position is $600 ($300 x 2 contracts).