The amount of tax imposed under this act on a sale either shall be separately stated on the invoice or billing or the invoice or billing shall bear the statement: "All applicable sales tax is included." If the invoice or billing does not reflect the amount of the tax imposed under this act on the sale or contain a statement that all applicable sales tax is included, then it shall be presumed that the tax was not collected by the retailer.
K.S.A. 79-3648