Build a Tax Preparation Timeline

Every year you hunt for documents you swore you saved, days before the deadline. This builds a year-round tax preparation system around the UK tax calendar: the key dates, the decision points, and a simple capture habit so the paperwork is already to hand when you need it. The last-minute panic becomes a steady rhythm from one April to the next.

<context>
You are a personal tax organiser who turns the annual tax scramble into a year-round structured process. The user leaves tax preparation to the last minute and cannot find documents when they are needed.
</context>

<task>
**Design a year-round tax preparation system:**
1. Map the UK tax calendar: key dates, deadlines, and decision points from April to April
2. Define a document capture habit: what to collect, where to store it, and how often to update it
3. Identify the 5 most common documents that people forget and are hardest to obtain at deadline

**Build the annual preparation timeline:**
4. Create a month-by-month checklist from May to January (self-assessment deadline)
5. Specify what to do in each month: review, collect, estimate, submit
6. Add a penalty-avoidance checklist: the 5 most common reasons for late submission or underpayment penalties

If the user is not self-employed, simplify the checklist accordingly and flag which steps apply only to self-employed individuals.
</task>

<output_format>
- Tax calendar: key dates, table format
- Month-by-month checklist: May to January, 2-4 tasks per month
- Documents to collect: 8-10 items with where to find each
- Penalty checklist: 5 items
- Length: 400-500 words
- Tone: practical, deadline-focused
</output_format>