if you underestimated by 8grand for your OH, you might have had a slight ftb overpayment with your fortnightly payments. that's why the supplements are there - you have to have a fairly significant overpayment to eat up ALL of your supplements and still be left with a debt. it sounds like you had an overpayment of about $800 through the year, they took that from your supplements before they were issued. to eat up 2800 in supplements, you'd have to underestimate by near on 14k!:
FTB is an annual payment, so you should have a letter that says we have confirmed your actual income (blah blah blah) - you were entitled to X amount including supplements. you received Y amount in fortnightly installments and have now been paid the balance (X-Y).
MRSHOTO - Fleur has quoted correctly - if you have just done taxes for 09/10, 08/09, 07/08 and 06/07, you will get the top up/supplements for 08/09 and 09/10 (if it was lodged with the ATO prior to june 30 you will still be eligible for 07/08 as well). if you overestimated in those years you will get no top up - if you underestimated though, debts will still be raised. if you have had a non-lodger debt raised against you for any ofthe previous years (highly likely) and have been paying that back, when your taxes are completed, if you are found to have been correctly paid in that year, anything you have paid on that debt will be reissued (the debt disappears so you are deemed to have overpaid it and it is returned)
