The deficit for the first eight months of this year is $600 million, compared with $400 million in the same period a year earlier, the Vietnam Economic Times newspaper said, citing Planning and Investment Ministry data.
According to the data, January-August exports rose 14.7 percent from a year earlier to $84.8 billion, while imports for those eight months were up 14.9 percent to $85.billion.
The government is expected to release details of Vietnam's exports and imports later this week.
In 2012, Vietnam had its first annual trade surplus in two decades, which economists attributed mainly to weak imports as the slowing economy hit consumer demand.
This year, trade has swung between deficit and surplus. There were deficits in February through May - the biggest being April's $937 million - and then there were surpluses of $286 million in June and $379 million in July.
In July, the Industry and Trade Ministry slashed its projection for the 2013 trade deficit to between $3 billion and 4 billion, from more than $9 billion.