A local-first bookkeeping helper for sole proprietors running English lesson businesses in Japan.
Blue Sheet Tax is a fully offline, browser-based bookkeeping tool designed for English conversation teachers (英会話講師) in Japan who file as sole proprietors (個人事業主) under the blue return system (青色申告). It covers the complete annual bookkeeping workflow — from recording monthly tuition payments and business expenses through to generating the reports required for year-end filing preparation.
All data is stored exclusively in the browser's localStorage. Nothing is transmitted to any server. The app can be used entirely offline once loaded.
Disclaimer: This application is a preparation aid only. All figures should be confirmed with a qualified tax accountant (税理士) before filing. The authors accept no liability for errors in tax calculations or filings.
| Screen | What it does |
|---|---|
| Dashboard | Year-to-date income, expenses, and estimated profit at a glance; filing readiness badge; quick-action shortcuts |
| Students 生徒管理 | Full CRUD for the student roster with lesson type, usual fee, and active/inactive status |
| Monthly Tuition 月謝入力 | Per-payment income recording with student snapshot, payment method, receipt reference, and envelope-signed flag |
| Expenses 経費入力 | Business expense entry across 8 blue-return categories with Included / NeedsReview / Excluded status workflow |
| Gas / Car ガソリン・車 | Fuel receipt log plus monthly business-use allocation with configurable percentage and deductible amount calculation |
| Assets 資産管理 | Asset purchase recording with automatic treatment suggestion (ordinary expense vs. depreciable asset) based on the ¥100,000 threshold, with manual override |
| Reports 帳票・レポート | Nine report types: Journal (仕訳帳), General Ledger (総勘定元帳), Cash Book (現金出納帳), Expense Summary (経費集計), Asset & Depreciation (減価償却一覧), Monthly Income (月別売上集計), Profit & Loss (損益計算書), Balance Sheet (貸借対照表), and City Hall Filing Helper (入力補助表) |
| Year-End Review 年末確認 | Seven-point checklist wizard with filing readiness badge and issue list |
| Export & Backup エクスポート | Full JSON backup/restore, four CSV exports, and multi-year management |
| Settings 設定 | Owner name, business name, default payment method, default gas business-use percentage, and asset threshold |
| Layer | Technology |
|---|---|
| Framework | React 19 |
| Language | TypeScript 5.6 |
| Build tool | Vite 7 |
| Styling | Tailwind CSS 4 |
| UI components | shadcn/ui (Radix UI primitives) |
| Routing | Wouter 3 |
| Charts | Recharts 2 |
| Persistence | Browser localStorage |
| ID generation | nanoid |
# Clone the repository
git clone https://github.com/penatechnologies/blue-sheet-tax.git
cd blue-sheet-tax
# Install dependencies
pnpm install
# Start the development server
pnpm devThe app will be available at http://localhost:3000.
pnpm buildThe static output is written to dist/public. Because the app is entirely client-side, it can be served from any static hosting provider (GitHub Pages, Netlify, Vercel, Cloudflare Pages, etc.) or opened directly from the file system.
blue-sheet-tax/
├── client/
│ ├── index.html # HTML entry point
│ └── src/
│ ├── App.tsx # Routes and top-level layout
│ ├── main.tsx # React entry point
│ ├── index.css # Global styles and design tokens
│ ├── components/
│ │ ├── AppLayout.tsx # Sidebar navigation shell
│ │ └── ui/ # shadcn/ui primitives
│ ├── contexts/
│ │ └── AppContext.tsx # Global state (wraps storage layer)
│ ├── hooks/ # Custom React hooks
│ ├── lib/
│ │ ├── types.ts # All TypeScript interfaces and enums
│ │ ├── storage.ts # localStorage read/write and CSV/report helpers
│ │ └── utils.ts # Shared utility functions
│ └── pages/
│ ├── Dashboard.tsx
│ ├── Students.tsx
│ ├── MonthlyTuition.tsx
│ ├── Expenses.tsx
│ ├── GasCar.tsx
│ ├── Assets.tsx
│ ├── Reports.tsx
│ ├── YearEndWizard.tsx
│ ├── Export.tsx
│ └── Settings.tsx
├── server/ # Minimal Express server (static file serving only)
├── shared/ # Shared type stubs
├── CHANGELOG.md
├── CONTRIBUTING.md
├── CODE_OF_CONDUCT.md
└── LICENSE
All application data is stored under a single localStorage key (blueSheetTax) as a JSON object conforming to the AppStore interface:
AppStore
├── schemaVersion: number # For future migrations
├── settings: AppSettings # Global preferences
└── years: Record<string, YearData>
└── YearData
├── students[]
├── tuitionEntries[]
├── expenseEntries[]
├── gasReceipts[]
├── gasAllocations[]
├── assets[]
├── reportState
├── reviewState
└── yearStatus
Each tax year is stored independently. The Export & Backup screen allows the full store to be exported as a timestamped JSON file and restored from a previous backup.
The sidebar year selector allows switching between any recorded tax year. The + button creates a new year with an empty YearData record. Students are stored globally (shared across years) while all financial records are scoped to the year they were entered.
The following blue-return expense categories are supported:
| English | Japanese | Risky |
|---|---|---|
| Supplies | 消耗品費（文具等） | No |
| Printing | 印刷費 | No |
| Consumables | 消耗品費 | No |
| Vehicle Fuel | 車両燃料費 | No |
| Travel / Transport | 旅費交通費 | No |
| Gift / Promotion | 交際費・販促費 | Yes |
| Meals (Review Required) | 飲食費（要確認） | Yes |
| Misc / Other | 雑費 | Yes |
Expenses flagged as "risky" are automatically set to NeedsReview status and highlighted for manual confirmation before filing.
Because all data lives in localStorage, it will be lost if the browser cache is cleared. Regular JSON backups via the Export screen are strongly recommended, particularly before clearing browser data or switching devices.
The JSON backup format is human-readable and version-tagged, making it suitable for long-term archival.
See CHANGELOG.md for the release history. Planned improvements include:
- Receipt photo filename linking with folder-open shortcut
- Monthly income bar chart on the Dashboard
- One-click carry-forward of the active student roster when creating a new tax year
- Depreciation schedule calculation (straight-line and declining-balance)
- Print-optimised CSS for all report views
Contributions are welcome. Please read CONTRIBUTING.md before opening a pull request.
This project is licensed under the MIT License.
Built with React, Vite, Tailwind CSS, shadcn/ui, and Recharts. Designed for the specific needs of English conversation teachers filing blue returns in Japan.