Each day, IBKR calculates and reports in the Interest Accruals section of the Activity Statement a forecast or accrual of interest earned or to be paid for the statement period. Around the first week of each month the interest which has been accrued during the prior month is "backed-out" or reversed and actual interest for the month is posted in the Cash Report section. These reversals, which occur once a month, should be close to the actual interest, although they may not always be exactly equal since accruals are a forecast of actual interest. 

Account holders should also note that accrued interest is only posted for any given reporting period when the amount exceeds $1, either positive or negative. Balances below $1 are retained and posted once, when aggregated with future accruals, the amount exceeds $1.