A spending category answers "what was this?" A budget bucket answers "which part of my plan pays for it?" Most of the time the answers line up, which is why many budgeting tools use one list for both. The trouble starts with the purchases where they don't.
One purchase, two questions
Say you spend $84 at a warehouse store. $54 is groceries; $30 is a birthday present for your sister.
$84 at a warehouse store
- $54Category: GroceriesBucket: Essentials
- $30Category: GiftsBucket: Fun money
With a single list, you have to pick one meaning. File the whole $84 as Groceries and your food spending looks inflated. File the gift under a "Gifts" budget line and you need a separate budget line for every kind of thing you might buy.
Keeping the two apart solves both problems. Categories can be as detailed as you like, because they are labels for reporting. Buckets stay few and broad, because they are the plan you check against during the month.
What each one is good at
Categories are for looking back. How much did dining out cost this year? Did the electric bill change after the new heat pump? Detailed, stable categories make those questions easy, and they don't need to change when your plan does.
Buckets are for deciding now. Is there room for a dinner out this Friday? A handful of buckets, such as Essentials, Fun money and Savings, tells you that at a glance. A plan with forty lines is hard to read on a phone in a checkout line.
The two also change at different speeds. You might rework your buckets every few months as income or priorities shift. Your categories can stay the same for years, which keeps old reports comparable.
A simple way to set it up
Start with three to six buckets
A common starting split is 50/30/20: needs, wants and savings. Adjust the percentages to your real income.
Keep categories descriptive
Groceries, Dining, Fuel, Utilities, Gifts. Add one only when you will actually look at it.
Give most categories a usual bucket
Groceries usually come from Essentials. That makes daily entry fast.
Override when it matters
The birthday dinner can be Dining in your reports and still come from the Gifts or Fun money bucket.
Move money, don't rewrite history
If groceries run high, move money from another bucket for this month. The purchase keeps its category.
When one list is enough
If you budget alone, have a short list of spending types and rarely split purchases, one list works fine. Adding a second dimension is only worth it when you notice yourself bending categories to make the budget come out right, or when two people read the same plan.
How Alluvium handles it
In Alluvium every transaction, and every split within one, has a category and a bucket. When you save an entry without a bucket, Alluvium suggests one from your rules, the payee's usual bucket, your plan and the category's usual bucket. You can change any of them.
Anything still without a bucket shows on the Plan tab under Unassigned, where you can file it by payee. To cover an overspent bucket, Move money shifts an amount between buckets for the month and keeps a list of moves you can undo. Each month has its own plan; a new month can start by copying the last one's buckets.
Alluvium is $7.99 a month or $59.99 a year on its own, or part of Apollo Suite. Prices are USD, checked October 3, 2026.