For transactions involving the provision of goods and services, the law requires businesses to prepare standard contracts and general terms and conditions to clarify pricing, payment methods, return and exchange policies, warranty obligations, and the responsibilities of each party.

These terms must be provided to customers prior to entering into any transaction to ensure transparency and reduce the risk of disputes.

Under tax and accounting regulations, any payment from 20 million VND and above must be made through non-cash methods such as bank transfers or other legally recognized electronic payment methods in order to be considered a valid transaction.

If a business fails to prepare a contract, does not issue an invoice, and still collects cash directly — including from foreign customers — for amounts exceeding 20 million VND, this constitutes a violation of payment regulations.

If the business intentionally fails to declare or pay taxes on these amounts, such conduct may be considered tax evasion under the Penal Code.