How to categorize expenses so the insights are useful

You have a list of expenses from last month. Hundreds of transactions on your bank statement. Now what? Without sensible categorization, this data is useless. Categories that are too broad won’t tell you anything. Categories that are too detailed will drown you in details. The art lies in finding the golden mean that gives clear answers and shows where to look for savings.

1. Forget ready-made category systems

Banking apps and budgeting programs offer predefined categories. Food, transport, entertainment, health. The problem? These universal divisions rarely fit your life.

The “food” category combines grocery shopping at the supermarket with dinner at a restaurant. Does that make sense? One is a necessity, the other is a pleasure. Treating them the same blurs the picture and makes it harder to draw conclusions. Instead of adopting someone else’s system, build your own. Based on how you actually spend money and what questions you want to ask yourself.

2. Distinguish necessary expenses from discretionary ones

The basic division that really works is distinguishing between what you can’t live without and what’s a matter of choice.

• Necessary expenses are those you cannot avoid. Roof over your head, basic food, commuting to work, medications. If you lost your income, these are things you’d have to maintain until the last moment.
• Discretionary is everything else. Better coffee instead of regular. New shoes when the old ones still work. Streaming, gym, cosmetics. You can give them up and survive.

This simple division immediately shows how much of your budget is flexible. If 80% of expenses are necessities, you have little room to maneuver. If 50% are choices, you have places to look for savings.

Simple rule: Be honest with yourself. Home internet is a necessity. But the premium package with all sports channels is a choice.

3. Divide necessities into subcategories

Within necessary expenses, it’s worth distinguishing a few subgroups. Each answers a different question.

• Housing is rent or mortgage payment, administrative fees, property insurance. This category shows how much just having a roof over your head costs.
• Utilities and bills are electricity, gas, water, heating, internet, phone. These expenses can often be optimized by switching providers or plans.
• Essential transport is fuel or tickets for commuting to work, car insurance, inspections. This is the cost you bear to earn money.
• Basic food is grocery shopping for home. Not restaurants, not cafes. Only what you buy to cook and eat at home.

Try this: Calculate what percentage of your income each of these subcategories consumes. The result may be surprising.

4. Create sensible categories for choices

Discretionary spending requires more thoughtful categorization. Here, the goal is to see what pleasures and conveniences your money goes to.

• Eating out is restaurants, fast food, cafes, lunch at work bought in town. Separate this from grocery shopping to see the true cost of not eating at home.
• Entertainment and hobbies is cinema, concerts, books, games, hobby equipment. Things you do for pleasure.
• Subscriptions and memberships is Netflix, Spotify, apps, memberships. Small amounts that add up to a significant sum.
• Impulses and small items is everything you bought without planning. Snack at the checkout, gadget on sale, something “because it was cheap.”

Behavioral trick: The “impulses” category is particularly important. When you see the sum of all unplanned purchases in one place, it’s easier to understand the scale of the phenomenon.

5. Use the one-question-per-category rule

A good category answers one specific question. If you don’t know what question a given category is supposed to answer, you probably don’t need it.

The “eating out” category answers the question “how much do I spend on not eating at home.” The “subscriptions” category answers the question “how much do I pay for things that work automatically.” The “commute to work” category answers the question “how much does earning money cost me.”

If a category doesn’t give a clear answer to a specific question, merge it with another or drop it entirely.

6. Don’t create too many categories

Five main categories is a minimum. Fifteen is a reasonable upper limit. More than twenty and you start wasting time sorting instead of analyzing.

Martha started with thirty categories. Coffee separate, tea separate, beverages separate, salty snacks separate, sweet ones separate. After a month, she gave up because categorizing every purchase took her half an hour daily. She simplified to ten categories and finally started drawing useful conclusions.

Shift in perspective: The goal of categorization isn’t perfect accounting. The goal is understanding patterns and finding areas for improvement.

7. Look for categories to cut and categories to protect

After a few months of categorizing, you’ll start seeing patterns. Some categories will point to savings opportunities. Others will turn out to be non-negotiable.

If the “subscriptions” category grows every month, it’s time for a review and cancellation of unused services. If the “health” category is high but concerns necessary medications, there’s nothing to cut here.

Proper categorization supports the broader process of managing household finances, where conscious spending decisions come from reliable data, not hunches. Once every six months, review your category list. Are all still being used? Is any missing? Don’t get attached to a system that’s stopped working.

Bonus idea: Compare proportions between months. Is the “impulses” category growing or shrinking? These trends say more than individual numbers.