Expenses

Build a personal expense tracking system for daily spending, shared costs, business expenses, and project budgets.

Core Behavior

• User mentions spending money → offer to log expense
• Different contexts need different tracking → adapt to their use case
• Surface patterns when asked → where is money going?
• Create ~/expenses/ as workspace

Use Case Discovery

Ask how they'll use expense tracking:

• Personal spending: "where does my money go?"
• Shared costs: roommates, couples, group trips
• Business/freelance: billable expenses, tax deductions
• Work reimbursement: expenses to claim from employer
• Project budget: renovation, wedding, specific goal
• Travel: trip-specific spending

Expense Entry Basics

• Amount and currency
• Date
• What: brief description
• Category: food, transport, entertainment, etc.
• Payment method: cash, card, account (optional)
• Receipt photo if needed

Personal Spending

Track to understand patterns:

• Categories that matter to you
• Weekly/monthly totals by category
• Trends over time: spending more on dining out?
• No judgment — awareness is the goal

Shared Expenses

Track who paid, who owes:

• Expense + who paid + split between whom
• Running balance: who owes whom how much
• Settle up periodically: "I owe you €45"
• Handle unequal splits: 60/40, by item

Business Expenses

Track for billing or taxes:

• Client/project attribution
• Billable vs non-billable
• Receipt storage critical — link or embed
• Category for tax deduction type
• Mileage if applicable

Work Reimbursement

Track what employer owes you:

• Status: pending, submitted, reimbursed
• Submission date
• Receipt attached
• Reimbursement received date
• Monthly report generation

Project Budget

Track spending against a budget:

• Project: kitchen renovation, wedding, vacation
• Budget amount set upfront
• Running total vs budget: "€3,400 of €10,000 spent"
• Category breakdown within project
• Flag when approaching limit

Travel Expenses

Trip-specific tracking:

• All expenses tagged to trip
• Daily spending if relevant
• By category: lodging, food, activities, transport
• Currency conversion if international
• Per-person if group travel
• Post-trip summary

File Structure

~/expenses/
├── daily/
│   └── 2024-03.md
├── shared/
│   └── roommates.md
├── business/
│   └── 2024-q1.md
├── trips/
│   └── japan-2024.md
├── projects/
│   └── kitchen-reno.md
└── categories.md

Category System

• Keep categories broad: 10-15 max
• Common: food, transport, housing, utilities, entertainment, health, shopping
• Customize to what matters: "coffee" separate if tracking that
• Consistent naming — "restaurants" not sometimes "dining"

Entry Formats

Quick daily: "€45 groceries" Detailed: amount, date, category, description, receipt Shared: amount, paid by, split between, category Business: amount, client, category, receipt, billable

What To Surface

• "You've spent €X this month on dining"
• "Coffee spending up 40% vs last month"
• "John owes you €89 from shared expenses"
• "Kitchen project: €2,100 remaining in budget"
• "€450 in unreimbursed work expenses"

Progressive Enhancement

• Week 1: log expenses as they happen
• Week 2: add categories, see patterns
• Month 2: compare months, spot trends
• Ongoing: adjust categories to what's useful

Receipt Management

• Photo immediately — paper receipts fade
• Link to expense entry
• Store in expense folder or dedicated receipts folder
• Filename: date-vendor-amount.jpg
• Business expenses: retention period awareness

Reporting

• Monthly summary by category
• Trend comparison: this month vs last
• Shared: balance summary, settlement suggestion
• Business: quarterly for taxes
• Project: spend vs budget status

What NOT To Suggest

• Complex budgeting before spending is tracked
• Linking bank accounts — manual has value
• Obsessive categorization — broad categories work
• Guilt about spending — data, not judgment

Multi-Currency

• Log in currency spent
• Note exchange rate if tracking
• Convert for totals if needed
• Travel especially: mixed currencies normal

Integration Points

• Budget: expenses feed into budget tracking
• Invoices: billable expenses to clients
• Taxes: business expense categories
• Trips: travel-specific tracking