A bank letter is an official document from your bank that provides important information about your business' official bank account. 1. Look into granting financial power of attorney for limited transactions.Your name, account number and sort code are on every cheque that you write, and we send those in the post. They need your banks information-your account number and the banks routing number so that your paycheck will automatically be put into your account. Bank Details on Company Letterhead. Recently got a new job or opened a new bank account? You should make sure your employer has the correct bank details. Verification Letters. Your scholarship payment is generally deposited directly into your bank account. When banks shut down accounts, they generally don't email, text or call you.