Start with questions you actually ask

If the question is whether commuting has become more expensive, a single transport category may be too broad when it includes holidays and occasional taxis. If the question is simply whether total everyday spending fits the plan, splitting every bus journey into separate labels adds work without changing the answer.

Write two or three decisions you want the budget to support. Then choose categories that reveal those decisions. The right number follows the purpose of the record, not a rule about how detailed a serious budget should look.

Test a mixed receipt

A hypothetical 90 supermarket receipt includes 65 of food, 15 of cleaning products and a 10 gift. If gifts have a separate annual allowance, recording the 10 there may be useful. If food and household supplies share one flexible allowance, splitting the other 80 may add no value. Keep the approach consistent so comparisons remain meaningful.

Avoid overlapping categories such as shopping, household and miscellaneous without definitions. The same purchase could land in any of them, making a trend depend on how you happened to label it that day. A brief note explaining the boundary is often enough.

Use a temporary holding category

Unclear transactions can go into a review category until identified. That is different from permanently burying them in miscellaneous spending. At the end of the review period, resolve the larger or recurring entries first. A small unexplained amount can remain labelled as such rather than receiving an invented description.

When a category grows repeatedly, inspect its contents before splitting it. Perhaps several unrelated costs need separate planning, or perhaps one large transaction explains the change. The structure should follow evidence.

Preserve comparisons when changing the system

If you combine or split categories, record the date and map old labels to the new ones where practical. Do not interpret an apparent drop in groceries as a saving if cleaning products were simply moved elsewhere.

After a month, ask whether each category answered a question or changed a decision. Remove needless detail and strengthen vague areas. A sustainable record that you understand is more useful than an elaborate taxonomy that is abandoned after a few weeks.