[BillAtHRST]

One not so minor point: you can't just "write off unpaid invoices" - if you're on an accrual basis (i.e., you record income when you bill), then you can "write off unpaid invoices", but what you're doing is simply subtracting the unpaid invoice from the income you earlier recorded; - otoh, if you're on a cash basis (i.e., you record income when you receive it), which is far more common for small biz, then you never recorded the income for that unpaid invoice, so attempting to write it off will get you in big trouble with the IRS (or the equivalent in the Great White North).