People who mistakenly send a mobile, online or phone banking payment to the wrong account will receive more help to claw their money back under industry changes.
Cash sent in error will now be returned to the person who made the mistake within 20 working days, in straightforward cases where there is no dispute that the money was sent by mistake, according to payment services Faster Payments and Bacs.
The rise of online banking and mobile payments means that more people are keying in bank account numbers and sort codes themselves - and a slip of the finger could mean that a payment ends up in the account of a stranger instead of that of the intended recipient.
The new procedures apply to payments sent using Faster Payments, which processes virtually every mobile, online and telephone banking payment between banks or building societies, and Bacs Direct Credit, which is used to pay nearly 90% of the UK workforce as well as to process pension payments, employee expenses, dividends, refunds and supplier payments.
The change applies to banks and building societies that connect directly to Faster Payments or Bacs Payment Schemes Limited, covering more than 95% of electronic payments made in the UK.
Implementation is also being rolled out across other banks and building societies during early 2016.
The new process builds on a voluntary code incorporated by banks in 2014, which means that as soon as someone tells their bank they have made a mistake with a payment, the bank should act within two working days.
Under the code, if the bank could not reclaim the funds immediately, it would investigate further and the customer would be told of the outcome within 20 working days.
Before the code was introduced in 2014, there was a lack of consistency over how banks dealt with their customers when the customer had made a blunder over a payment and some problems could take months to sort out.
The new announcement means that if there is clear evidence of a genuine mistake, the bank that has received the cash will stop the money being spent by the person whose account the money has gone into.
But to balance the rights of all customers, the receiving customer will be contacted by their bank to give them the chance to dispute the return of the funds.
Where claims are less clear-cut, no funds will be removed without the consent of the recipient, the payment schemes said.
The changes do not mean, therefore, that someone making a wrong payment is guaranteed that they will get their money back - so people should always check before they click when transferring cash.
Craig Tillotson, chief executive of Faster Payments, said: "Mobile, online and phone banking customers now send well over a billion payments every year.
"The most important advice is to make sure you get the sort code and account number correct when sending any payment but, if you do make a mistake, today's announcement means more help is on offer, while also ensuring the recipient of funds is treated fairly too."
Michael Chambers, chief executive of Bacs, said: "It is absolutely right that anyone who is out of pocket as a result of a mistake can get that money back."
The improvements were also welcomed by the Government.
Harriet Baldwin, Economic Secretary to the Treasury, said: "More people than ever are banking online, taking advantage of being able to make payments 24 hours a day, seven days a week, so it's vital that everything possible is done to prevent mistakes from happening."