After ten years of construction and $51 billion in funding the National Broadband Network is on track to be completed by next year, the federal government says.

Three-quarters of Australian households can now connect to the network, including 92 per cent of regional homes.

Communications minister Mitch Fifield on Tuesday said five million households were using the NBN, which has contributed $1.2 billion to gross domestic product.

Meanwhile, the consumer watchdog is concerned households on lower incomes are paying too much for broadband plans.

The cost of basic NBN plans are now more expensive than what most consumers pay for equivalent ADSL plans, the Australian Competition and Consumer Commission says.

ACCC chair Rod Sims told the CommsDay Summit in Sydney on Monday low-speed NBN plans offered to new customers are at least $10 per month higher than what consumers paid for equivalent ADSL plans.