Categorize Expenses Automatically

Create a new spreadsheet named: Expenses — [MONTH] — working Add a tab called Import. Paste or use File → Import to bring in your bank/card CSV. Standardize columns to exactly these headers (insert/rename columns as needed): Date | Description | Amount | Source (optional) | Category (leave blank for now) Fix common import problems: - Remove merged cells and duplicate header rows - Ensure one logical transaction per row (no multi-line descriptions that belong to separate charges) Sort by Date ascending. Select the header row plus your first batch of transactions (aim for ≤60 rows in the next steps) and copy (Cmd/Ctrl+C). You will paste this into Claude in step 3.

Open https://claude.ai and start a NEW chat. Keep this same chat open through steps 3 and 4. Paste the following block, replacing the bracketed sections with your real data: --- MY CATEGORY TAXONOMY (FINAL — do not add labels): [List each category with a one-line definition] REAL EXAMPLES (3 per category): [Paste short examples you have actually seen on statements, or realistic placeholders] DISAMBIGUATION RULES (hard constraints): - Example: If Description contains AWS, DIGITALOCEAN, or GITHUB → category Software (not Professional services). - Example: If Description contains UBER or LYFT and text mentions airport or flight → Travel (not Meals). GLOBAL RULES: - Do not invent new category names. - If a transaction cannot be mapped with high confidence, use exactly: Needs review (do not guess toward the closest category). --- Then send: Echo my taxonomy back as a numbered markdown table. Do not classify transactions yet. List only ambiguous merchant TYPES (not random new categories) where my rules might need tightening.

In the SAME Claude chat from step 2, paste your copied sheet data as a markdown table OR tab-separated values. Above the paste, send: --- Use ONLY the taxonomy and rules already defined in this conversation. Task: Assign exactly ONE category per row from my numbered list. Output a markdown table with columns EXACTLY: Row | Suggested_category | Confidence_High_Med_Low | One_line_reason | Flag_if_split_Yes_No Rules: - Suggested_category must be one of my categories OR exactly Needs review. - One_line_reason must quote or closely paraphrase words from Description (no invented merchants). If you have more than ~40 transaction rows, split into two pastes in this same chat (Part 1 / Part 2) and keep row numbering continuous. After both parts (if split), send: Reconcile: the same Description substring must map to the same category across all rows unless Amount sign differs (e.g. refund vs purchase). --- Paste your rows after that instruction block.

In the SAME chat, copy back only rows where Suggested_category is Needs review OR Confidence is Low. For each repeating pattern, decide: (a) Approve a one-sentence new IF/THEN rule using Description substrings, Source, or an Amount threshold, OR (b) Keep as Needs review for human judgment this month. Then send: --- Output a block titled exactly: RULES_ADDENDUM Content: bullet list ONLY. Each bullet must be testable (substring, Source value, Amount >/< threshold). No bullets like "use judgment" or "when it feels like travel." Maximum 10 bullets. Do not re-print the full transaction table unless I ask. --- Edit the RULES_ADDENDUM bullets yourself if any line is vague before you move on.

In your spreadsheet, add a tab named Master. Paste into Master: - Your final taxonomy table - The full RULES_ADDENDUM from step 4 - Any disambiguation lines from step 2 that must never drift Back on the Import tab, fill the Category column using Claude’s Suggested_category output. Use Paste special → values only (avoid fragile live links). In Master, add a cell labeled Next_month_starter_prompt and paste a short template you will reuse, for example: "Apply ONLY the taxonomy + RULES_ADDENDUM on the Master tab to the new rows I paste below." Optional: Duplicate Import to a tab Template, delete the data rows, and keep headers for future months.