HMRC brown envelope lands. Paste it in, we'll tell you what it actually means.
For sole traders, subbies and small firms who get an HMRC letter and can't tell if it's routine, urgent, or a prelude to a compliance check.
Sound familiar?
- “I've just got a letter about my self-assessment. It reads like Klingon.”
- “They say I owe £3,400 and I don't know if that's right.”
- “It mentions a 'compliance check'. Am I about to get audited?”
- “The deadline is in two weeks and I don't know what they actually want.”
What this tool does
Matches your letter reference code and keywords to the most common HMRC letter types, determinations, assessments, compliance checks, late filing and SA302 requests, and explains what it is, what it wants, and what the deadline really is.
SA250
Notice to file a tax return
HMRC wants you to file a Self Assessment return. You must do this even if you owe nothing. Deadline is on the letter.
SA300
Tax calculation (what you owe)
HMRC has calculated your tax bill based on your return. Check the figures match what you filed. Payment date is shown.
SA302
Tax calculation confirmation
A copy of your tax calculation, often needed for mortgage applications. Not a demand for payment.
SA316
Statement of account
Shows what you owe and what you have paid. Check the balance. If it shows zero, you are up to date.
SA326D
Penalty for late filing
You missed the filing deadline. £100 penalty initially, rising to £10 per day after 3 months, then further penalties at 6 and 12 months. File immediately to stop penalties growing.
SA370
Penalty for late payment
You missed a payment deadline. Interest is being charged daily. Pay as soon as possible or call HMRC to set up a Time to Pay arrangement.
P800
Tax calculation (PAYE)
HMRC thinks you have paid too much or too little tax through PAYE. Check the tax code they used and the income figures.
P2
PAYE coding notice
Your tax code for the coming year. Check it is correct, especially if you have multiple income sources.
CIS300
Subcontractor verification
Confirmation that a contractor has verified you for CIS. No action needed unless the details are wrong.
CIS301
CIS deduction statement
Shows CIS deductions made from your payments. Keep this — you need it for your Self Assessment return to claim back overpaid tax.
CIS304
Change of CIS status
Your CIS deduction rate is changing. Could be moving from 30% to 20% (good) or 20% to 30% (bad — usually means you missed a filing). Check why.
DEBT
Debt collection warning
HMRC is threatening to pass your debt to a collection agency. Call them immediately on the number on the letter. You can usually set up a Time to Pay plan.
COMPLIANCE
Compliance check opening letter
HMRC is investigating your tax affairs. Do not ignore this. You have rights. Consider getting an accountant. Most compliance checks are routine and resolve without penalties.
What the law actually says
- •HMRC must give you the statutory basis for any determination or assessment. You have the right to appeal within 30 days in most cases.
- •A compliance check (Code of Practice 8 or 9) is a formal investigation. You do not have to answer every question, some are fishing and you can narrow the scope.
- •Ignoring HMRC letters almost always makes the position worse. Penalties compound and appeal windows close.
What to do next
Get monthly SiteKiln updates?
One email a month. Rate changes, new tools, guide updates relevant to you. No spam, unsubscribe any time.