Fraudsters are being blocked from using so-called number spoofing to trick people into believing they had received a call from genuine tax officials.
HM Revenue and Customs (HMRC) said there were more than 100,000 attempts by fraudsters last year to make people pay spurious tax bills.
Part of the fraudsters’ tactics was to manipulate the caller number display to show HMRC’s actual phone numbers.
Now HMRC has put a block on these numbers, so they cannot be shown.
It has worked with phone companies to introduce the technology.
‘Huge step forward’
Number spoofers also pretend to to be calling from banks, trying to get direct access to accounts in order to empty them of cash.
Banks say they are working with the telecoms regulator Ofcom on ways they can crack down on the practice as well.
Financial secretary to the Treasury Jesse Norman said: “This is a huge step forward in the fight against phone fraud.
“HMRC’s new controls will help to protect thousands of hardworking taxpayers and their families from these heartless criminals.”
In 2018, HMRC received reports of 104,774 attempted phone scams, compared with just 407 in 2016.
Since the controls were introduced in April, HMRC said it had not received a single report of the spoofing trick being used.
“Number spoofing can be incredibly hard to spot, so it is good to see HMRC, one of the most impersonated firms, taking action to stop fraudsters from exploiting their helpline number and identity,” said Gareth Shaw, from consumer watchdog Which?.
“A cross-sector approach is needed to tackle fraud, and it is now vital other public bodies and firms that are commonly impersonated follow this example and work with telecoms companies and Ofcom to stop fraudsters spoofing their numbers and targeting victims.”