The UK financial watchdog has said consumers will have until August 29, 2019 to make a claim that they were mis-sold debt repayment insurance, setting a deadline for complaints about Britain's costliest financial services scandal. 

Banks including Lloyds and RBS have collectively paid out more than £24 billion to customers who were mis-sold payment protection insurance (PPI). 

The Financial Conduct Authority (FCA) had previously suggested June 2019 as the deadline, but has now pushed it back after several months of consultation. 

The regulator will launch a major communications campaign in August this year to help consumers to decide whether to make a claim or not. 

Banks are likely to welcome the news of certainty around the deadline for complaints, executives at Britain's biggest banks previously told Reuters, because of fears the deadline could have been extended beyond 2019. 

The FCA stressed that most consumers should be able to handle making their claims themselves, rather than using the many claims management companies that assist with complaints in exchange for a slice of the payout. 

The regulator also set out guidelines for how firms should handle complaints by customers who were sold the insurance by firms that received large undisclosed commissions on the sale, after a court case on this issue. 

The FCA said that if commission levels were more than 50% and were not disclosed, then firms should presume that "the failure to disclose commission gave rise to an unfair relationship." 

In those cases, the firms will have to contact customers to tell them they may have an eligible claim, the FCA said, even if they have previously had a complaint rejected. 

The PPI policies, designed to protect borrowers in the event of sickness or unemployment, were found to have often been sold to people who would have been ineligible to claim. 

Regulators have had rules for PPI claims in place since 2010 and normally a deadline of three years is set, but surveys showed many people were unaware they had bought the product.