That is, in your accounting reports/balance sheets, you transfer the cost of extra bandwidth to the advertising and then 'write off' the amount (i.e. remove the amount from your accounting balance).
Example : if you are writing off $150 worth of extra bandwidth, you transfer the $150 to your advertising costs on your balance sheets, then deduct that amount from your overall profit/costs/etc. Same thing happens with bad debts (debts that some ppl can't repay for whatever reason, length of time, etc.)
(Disclaimer : I'm not an accountant, and this should not be construed as accounting advice - someone can correct me if I'm wrong).
My 2 Cents....
(or is that 2.2 cents inc. GST...?)
Have a think about this : Programming is like sex. Make a single little mistake, and you'll be supporting it for the rest of your life.