HMRC has provided guidance after a customer received a message they were not expecting.
The customer contacted the group as they had received a text message with an access code.
Yet, they claimed they had not tried to access their account.
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The worried customer asked: "Does this mean my account has been compromised or was it sent in error?"
HMRC responded to say there may be an innocent reason for the message.
The group said: "It may just be somebody that has entered the wrong digits."
Nevertheless, the tax authority did issue some further guidance to protect the person's account security.

The group warned: "For security reasons, avoid clicking on any links or responding.
"You can log into your account separately and check your account, review security settings and change password for added security if you wish."
You can access many HMRC services with a personal tax account.
Here you can see your income tax estimate, check your state pension entitlement and submit and manage a self assessment tax return.
The account will also show you your National Insurance number and you can also view your simple assessment tax bill if you have one.
To set up an account, you will first need to create a Government Gateway ID on the gov.uk website.
Another way you can monitor your tax affairs is through the HMRC app.
You can use the service to see your tax code, as well as details of your state pension forecast, income and benefits payments.
You can also see an estimate of the tax you need to pay and you can make a self assessment payment or a simple assessment payment.
The app can also be used to check if you can pay to cover any gaps in your National Insurance record.
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