Can jobs arising outside the contract in Vietnam be accepted?

In Clause 2, Article 13 of Decree 37/2015/ND-CP guiding the construction contract, it is stipulated: 

2. Acceptance and handover of finished works:

a) Agreements on procedures for acceptance and handover of the works by the parties to the contract must conform to the provisions set out in the Law on Construction Quality Control.

b) Works to be accepted and handed over; foundations for acceptance and handover; procedures, date of acceptance and handover of finished works; personnel involved in acceptance and handover; forms; signers, written records, reports must conform to the law provisions and be agreed by the parties to the contract.

c) Only products that meet quality requirements as prescribed in Clause 1 of this Article are accepted and handed over.

d) As for the works to be inspected and accepted before moving on to other works, the contractor must make prior notice to the employer for inspection as prescribed by the Law on Construction Quality Control.

dd) As for defective products (failing to meet requirements as prescribed in the contract), they must be remedied or eliminated otherwise.  Any party that commits the fault shall incur the entire cost for remedial work, re-appraisal and implementation progress.

Thus, according to the regulations in Vietnam, for the work arising outside the contract, it depends on how the parties agree with each other in the contract. In case there is no agreement on the additional issues, it may be based on the current agreement to carry out the acceptance. 

Best Regards!