Broadband providers will have to include the price of line rental in their headline costs from October, the advertising watchdog announced today.

Until now broadband providers have been able to claim that their broadband costs just a few pounds – and only detailing in the small print that the cost excludes line rental, which often adds just shy of £20.

The move is a victory for This is Money, after years of calling for pricing to be more upfront.

We have argued that if a cost is compulsory when signing up for a service, it should not be excluded from the headline price. Since it is rarely possible to take out broadband without line rental, line rental must therefore be included.

The lack of clarity has meant that some broadband providers have been able to have flashy deals and advertising campaigns with eye catching prices for broadband, only for households to find out that to get the cheap price they'll have to pay the best part of £20 a month on top for line rental.

Playing fair: From October broadband suppliers must be upfront about total costs by including landline rental in the headline price

The move by the Advertising Standards Authority come after it published a joint survey with Ofcom in January, which found consumers had enormous trouble working out the true cost of broadband from common adverts.

It showed participants current broadband ads and asked them to identify from the ads how much broadband would cost every month.

Only 23 per cent of participants could correctly identify the total cost after the first viewing, while 22 per cent were still not able to identify the correct cost after even a second viewing.

A total of 81 per cent of participants were unable to calculate correctly the total cost of a broadband contract when asked to do so.

Since then, the ASA has been working with the industry and consumer groups to work out how to make things better for households. The result is new rules that will come into force on October 31 this year.

Fighting: This is Money has been calling on greater transparency in broadband pricing

TalkTalk has already announced that it will no longer separate out line rental costs from its broadband price and other suppliers are likely to follow shortly.

It would have been difficult for a single supplier to switch their pricing while others continued to exclude line rental costs as their deals would have seemed much less competitive. Once all suppliers are forced to include line rental costs, they will be comparing like-for-like again.

The ASA changes include recommendations that broadband ads show all-inclusive upfront and monthly costs – without separating out the line rental; greater prominence on ads for the contract length and any post-discount pricing, and greater prominence for upfront costs.

ASA chief executive Guy Parker said: 'We recognise the importance of broadband services to people's lives at work and at home. The findings of our research, and other factors we took into account, showed the way prices have been presented in broadband ads is likely to confuse and mislead customers.

'This new tougher approach has been developed to make sure consumers are not misled and get the information they need to make well-informed choices.

'We'll support the broadband industry as they move towards changing their approach in time for the October 31 deadline.'

Culture minister Ed Vaizey also called for changes earlier this year, accusing telecommunications providers of charging households for landlines that they often did not use.