At the very bottom of the Trade-section-page you can find 2 values, one for the amount of resources you can loot without penalties and the actual amount you already looted, i guess.

Now I am wondering, how big the penalties are if you looted more than the limit and for what time-intervall these values count.
Will they reset? If so, when? Are they recalculated each hour/day/week? Is that a monthly limit? Does that limit increase, if so how?
Oh and do contaminated resources by queens also count into that amount and how about salvaged debris or is it only for loot from direct attacks?

Sorry, but i didn't find anything about this yet...

If you looted more than the limit, you will get penalties, depending on the points difference bettween you and your attacked opponet, but not more then 66%.

This limit depends on your monthly output (25% in unires equivalent). You can increase the limit, increasing your production. The limit recalculated after a month of each operation.

As for resources contaminated by queens - They don't count into that amount.

Good to know, thank you very much.