Can I appeal against a self-assessment calculation?

Based on the HMRC Self Assessment Manual, you cannot appeal against a self-assessment calculation itself. The manual specifically states that taxpayers have “no right of appeal” against:

• Revenue calculations
• Correction notices (though you do have the right to reject HMRC’s corrections)

However, you can appeal against certain related items that might affect your self-assessment calculation:

What you CAN appeal against:

Charge-based items:

• Revenue assessments
• Revenue amendments to your SA return
• Jeopardy amendments
• Various penalties (late filing, late payment, etc.)

Non-charge-based items:

• HMRC requirements to produce documents
• Continuation of an enquiry into your return
• Revenue amendments of partnership statements

Important distinctions:

• Self-assessment calculation = Your own calculation on your return (not appealable)
• Revenue calculation = HMRC’s calculation (not appealable)
• Revenue assessment/amendment = HMRC’s formal challenge to your figures (appealable)

What to do instead:

If you disagree with HMRC’s calculation, you should:

1. Check if it’s actually a Revenue assessment or amendment (which would be appealable)
2. If it’s a correction notice, you can reject the correction
3. Consider whether you need to file an amended return yourself
4. Seek professional tax advice if the matter is complex

Appeals must be made in writing within 30 days of receiving the notice, though HMRC allows 37 days to account for postal delivery time.