There was no 100k minimum before, then the did away with paying interest altogether - I guess competitive pressure with interest rates rising above zero has forced their hand.
Why do you say this? They didn't do away with paying interest. Interest rates just went below the base rate less the 25-50 bps. They pay more interest now than many banks. Take at your statement. I'm getting .66% on the balance over 10K
I remember it was stated policy that they did not pay interest. i remember reading that with utter disbelief. That said to be fair they were charging a much lower cost of borrow than anywhere else retail and likely the policy was aimed at rewarding those who generated comm for IB with lower borrow cost subsidised by not paying on inactive cash balances. They do now pay interest likely because when interest was 25BP or whatever the fact that somebody else might be paying 25BP was likely not enough to make someone move an account. As interest rates increase it becomes more of an issue.
You are wrong on this for USD. They have always paid interest (when base rates are > 25 bps) on cash balances over 10K.
They have always paid interest but when interest rates were lower, their interest rate calculation (based on US Treasuries at one point, LIBOR at another, maybe something else now) resulted in a negative interest rate (so obviously no interest when that happens). Now that interest rates have risen, you are getting a positive interest rate and so you are getting interest.
In my accounts, interest accruals started in December 2016. They stopped paying any interest when fed funds rate went the lowest (cannot remember when). Only accounts with 100K or more are getting interest (accrues daily and posted monthly). I have accounts with 30K and 25K - I don't see any interest payment. They do say 100K or more is required for earning interest. "For the purposes of crediting interest on either long settled cash balances or short stock collateral values, only accounts with Net Asset Value (NAV) exceeding USD 100,000 will be eligible to receive credit interest on long settled cash balances." https://www.interactivebrokers.com/en/index.php?f=1595
That is how I remember it - suddenly started paying interest a few months ago and before not and statement to that effect.