When “Miss B” received a missed call from an unrecognised number, she did an internet search, and found it belonged to her local courthouse.

Later that day, she received a second call from the same number. The caller claimed to be from the court, and said she needed to urgently pay an £849 outstanding debt to HM Revenue and Customs (HMRC) – or risk being arrested.

She paid and then received a WhatsApp message, asking her to send a copy of her passport and her driving licence to validate the payment.

When she was told to provide her bank details, she became suspicious and contacted her bank, Santander (santander.co.uk), who advised it was a scam.

Scams can appear very plausible, and phone numbers can be “spoofed” to appear genuine. Tax scammers may be particularly likely to strike around now, when people are filing their self-assessment returns, as the end of the tax year in April approaches.

The self-assessment tax return deadline was January 31, but HMRC is waiving penalties for one month for late filing of tax returns and late payments.

Anyone unable to file by the usual deadline will not receive a late filing penalty if they file by February 28.

Chris Ainsley, head of fraud control at Santander UK, says: “By taking on the persona of the HMRC, criminals are trying to intimidate their victims by impersonating an institution most of us recognise and trust.

“With the February extension to the self-assessment deadline fast approaching, we expect to see a significant increase in HMRC scams over the coming weeks. Don’t let criminals get away with it. Always check with HMRC directly before acting.”

Scams may be initiated through email, text, phone or WhatsApp. Santander warns contact details, such as the caller ID, can be easily made to appear genuine.

Fraudsters may provide a link for the customer to complete their details and pay the money they say is owed. In other instances, scammers may use temptation rather than threats, claiming people are owed a “tax rebate” – and asking them to provide personal details.

Once the customer has shared details or paid, this can be the end of the scam – but Santander warns sometimes people can be scammed twice. They may be contacted again, this time by someone pretending to be their bank’s fraud team, using the details previously shared.

They are told they have been scammed, and should move their money to a “safe” account – in reality belonging to the criminals. Many banks have introduced “confirmation of payee” when making payments online, so customers can check the name matches the account number.

If in any doubt about who you’re talking to, stop the conversation. If you’ve been scammed, tell your bank and the police. Suspect texts can be forwarded to HMRC on 60599, and emails to [email protected].

HMRC recently said there had been a sharp fall over the past year in reports of scams impersonating it, reflecting its work in tackling fraud.