First of all, according to the Provisional Regulations of the People's Republic of China on Business Tax, units and individuals that provide taxable services, transfer intangible assets or sell real estate are taxpayers of business tax. Therefore, if the matchmaking service fee of 6800 yuan is not invoiced, there may be a problem for business tax payers.
Secondly, according to the Measures for the Administration of Invoices in People's Republic of China (PRC), units and individuals that sell goods, provide services and engage in other business activities collect money from outside, and the payee shall issue invoices to the payer. Therefore, if the matchmaking service fee of 6,800 yuan is not invoiced, there may be a problem of violating the invoice management measures.
To sum up, there may be some problems in the failure to invoice the matchmaking service fee of 6800 yuan. It is recommended to consult relevant departments for specific information.