The answer depends upon the method of deposit.  In the case of deposits made via ACH, any interest accrues from the date the deposit arrives through the four-business day credit hold period after which it is credited to the account.  In the case of check deposits other than Bank Checks, no interest is accrued during the credit hold period.  Bank Checks and wire transfers are credited to the account effective upon receipt and are therefore not subject to any credit hold.

Interest paid to you varies with market conditions.  For information regarding the amount of interest currently paid on credit balances see www.interactivebrokers.com/interest