You can partially automate Google Sheets expense tracking using three built-in tools: Google Forms for auto-appending rows, IMPORTRANGE for consolidating multiple sheets, and Apps Script for auto-categorization and scheduled summaries.
Google Forms is the easiest starting point — create a form with Date, Merchant, Category, Amount, and Notes fields, link it to your Sheet, and every submission auto-creates a timestamped row. Bookmark the form on your phone for fast mobile logging.
Apps Script (Extensions → Apps Script in your Sheet) lets you write JavaScript functions that trigger on form submit or sheet edit. The most useful function for expense tracking is auto-categorization: the script reads the Merchant column on each new row, checks it against a keyword-to-category dictionary (e.g. "amazon" → "Office Supplies", "zoom" → "Software & Subscriptions"), and writes the matched category automatically. Consumer accounts get 90 minutes/day of execution time — plenty for expense tracking. Add a time-based trigger to email yourself a weekly SUMIF summary without opening the sheet.
What Google Sheets cannot automate regardless of script complexity: reading email receipts (requires significant Gmail API development), OCR on receipt photos (requires Google Cloud Vision API + custom parsing), and bank transaction import (requires third-party Plaid integration). These are hard architectural limits, not script complexity problems.
The practical ceiling is roughly 30–60 receipts per month. Past that, the time spent maintaining the automation (updating the merchant dictionary, fixing uncategorized rows, handling new vendors) exceeds the time saved. ExpenseBot's Google Sheets integration provides the "fully automated" version — Gmail auto-scan, OCR, Schedule C categorization, and automatic row writing to your existing Google Sheet. See https://www.expensebot.ai/google-sheets-expense-tracker and https://www.expensebot.ai/blog/automate-expense-tracking-google-sheets.