It’s common for employers to notice changes in an employee’s tax code or deductions without knowing the cause. One of the most frequent reasons is an HMRC-issued tax notification—specifically a P6 form. Understanding how these updates work is essential for accurate payroll processing and clear communication with employees.
What Is a P6 Notification?
A P6 form is a tax code notification from HMRC. It informs employers of updates that affect PAYE (Pay As You Earn) calculations—such as:
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Tax code changes (e.g., from 1257L to 1270L)
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Adjustments for underpaid tax
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Updates due to benefits in kind or personal allowance changes
These updates are typically triggered by:
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An employee submitting a Self Assessment return
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Changes in personal circumstances (e.g., marriage, multiple jobs)
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HMRC reconciliations from the previous tax year
How Employers Might Notice a Tax Change
During payroll processing, employers might observe that:
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An employee’s tax code has changed
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New tax adjustments are applied (e.g., additional deductions)
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The tax deducted from pay is higher or lower than expected
These changes are not initiated by the employer—they are the result of HMRC updates via P6 notifications.
How to Check for P6 Notifications
There are three main ways to verify the source of a tax code change:
1. HMRC PAYE Online
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Log into the HMRC PAYE Online portal
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Check for new messages or tax code notices
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P6 notices will show the updated tax code and the effective date
2. UK Payroll Integration
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Bob’s UK Payroll is integrated with HMRC
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P6 notifications are automatically imported and applied
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Review HMRC Documents Section or the employee profile to trace the update
3. Ask the Employee
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HMRC may contact the employee directly
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Employees can view their tax code and allowances in their Personal Tax Account
Best Practices for Employers
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Stay informed: Regularly check for new HMRC notifications—especially around tax year changes and after budget updates
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Communicate clearly: If an employee questions a change in take-home pay, explain that the tax code change likely came from HMRC and encourage them to check their Personal Tax Account
Important to Know
Employers are legally required to use the tax code issued by HMRC. Once applied, it cannot be changed unless a new notification is received.
Bob’s UK Payroll integrates directly with HMRC to automate these updates. If you haven’t set this up yet, follow the guide here:
Connect with HMRC →