<address of debtor>
DEBT OWED TO <NAME>
You are indebted to us in the amount of <$Y> for unpaid tax invoices dated <x> and <y> in relation to <services/goods> rendered to you by us.
We demand that you repay the full amount of <$Y> into our bank account, details of which are set out below (or, <by sending a cheque to us>) by 4pm on <date>, failing which we intend to instruct our solicitors to commence proceedings against you for the recovery of the sum without further notice. If that proves necessary, we will further recover court costs, professional fees and interest from you. We trust that will not be necessary.
<your bank account details here including name of account, bank, BSB and account number>