The memo line is a place for a reminder or message to the check writer or business. The memo can be a reminder of when and why the payment was made, or it can provide account information for a business. For example, it may be used to indicate that a check was written in May, but it was for an April payment.
To assign payments accurately, the IRS and medical companies request memos. The IRS requires the tax year, tax form and social security number for payment purposes. Medical companies usually want the account or invoice number. Any memo for a business is a verification of the name with an associated account number or ID number.