IB Same Margins for Front and Back Contracts?

I'm using TWS latest. Works for me. (Beside the ton of bugs TWS has. But switching between stable/latest/beta doesn't change that ).

 

I think that is the setup, not TWS itself.

 

If you don't want to use TWS you can also use IB's online contract database and search for the information there: https://www.interactivebrokers.com/en/index.php?f=463

 

Yes, but for whatever reason the margin requirements shown there are the same for all expiry dates. By the way, this function can be accessed from TWS too: right click ticker symbol > Financial Instrument Info > Details

 

Don't take any information about IB margin as universal. It can vary depending on where your account is booked for some products.

CLF front month is interesting, presumably they don't want you to trade that due to physical delivery.

 

If you look carefully, for IRA account, it has same margin for all calendar months. At least for CL. Check it.