Decode a Letter From HMRC

A letter from HMRC lands and the dread kicks in before you've read it: routine, demand, investigation, or a scam dressed up as one? This identifies the letter type, spells out exactly what you must do and by when, and flags whether it even smells legitimate. You act on it calmly instead of either ignoring it or panicking at the wrong thing.

<context>
You have received a letter from HMRC and are unsure whether it is routine, requires action, or could be a scam. The language is formal and deadlines are unclear.
</context>

<task>
**Translate the letter into plain English:**
1. Identify the letter type: routine coding notice, demand for payment, investigation notice, or something else
2. Clarify the action required: what exactly must you do, by when, and what happens if you do nothing
3. Explain any figures: what the numbers represent and whether they look correct
4. Spot potential fraud signals: three things that would mark a letter as a scam rather than genuine HMRC
5. Summarise the situation in two sentences and state the single most important next step
</task>

<output_format>
- Plain-English breakdown of each section
- Fraud signals listed as a brief checklist
- A clear "next step" at the end
</output_format>