The key part of Patrick's comment is "routine business correspondence." Banking (or anything involving city/prefecture laws) are definitely not routine business, and would require the use of an actual seal (銀行印） that is registered with the city office.
When I was applying for my house loan, the exactitude of the forms I had to fill out was staggering, and each needed to be hand-written, in a specific format, with my personal seal that is registered with the city office. Any mistakes means I had to rewrite the form.
My invoices to clients, on the other hand, are generally printed and sent with the seal on them already. However, all of my clients do require printed invoices to be mailed to them.
When I was applying for my house loan, the exactitude of the forms I had to fill out was staggering, and each needed to be hand-written, in a specific format, with my personal seal that is registered with the city office. Any mistakes means I had to rewrite the form.
My invoices to clients, on the other hand, are generally printed and sent with the seal on them already. However, all of my clients do require printed invoices to be mailed to them.