6. 예산 실전 예제

ENGLISH

6. Budgets — A Worked Example

This chapter follows one imaginary example from start to finish. Every figure is a round number you can do in your head, and none of it is real user data. The goal is that by the end you can answer "why does a budget move differently from an account balance?" yourself.

The setup

• Budget period: monthly, starting on the 1st (calendar months).
• Salary: $3,000 paid into the bank account on the 23rd of each month.
• Three budget groups, each with different carryover switch settings (the switches are explained precisely in step 3).

Say that on 1 August the Available to allocate (pool) was $1,100, and exactly 800 + 200 + 100 = $1,100 was allocated across the three groups, leaving the pool at $0.

Step 1 — Spend through August

Entering each expense under its category increases the spent amount of the budget group that category belongs to.

• Living group: $650 spent on food, transport, and so on → spent $650, left 800 − 650 = $150.
• Travel Fund: nothing spent this month → left unchanged at $200.
• Cafe/Snacks: more than expected, $130 spent → left 100 − 130 = −$30 (overspent).

A negative amount left in Cafe/Snacks is not an error; it is a signal that you spent more than planned this month. It does not mean your account went negative — it means you went past the limit you set for that category.

Step 2 — Record the 23 August salary as real income

Enter the $3,000 salary as an income transaction into the bank account. At that moment Available to allocate (pool) increases by $3,000. The August budget period has already been allocated, so this money becomes the funding for September.

There is no feature for allocating a salary in advance. You can only allocate money once it has been recorded as a real transaction. "I am due to be paid later this month" does not increase the amount available to allocate.

Step 3 — Close out August and move into September

Every budget group has two carryover switches that you turn on and off separately for each sign of the amount left — Rollover remaining amount (when positive) and Rollover overspending (when negative). Switching one on keeps that amount in the same group; switching it off moves the amount to the Available to allocate (pool). The three groups in this example are set up as follows.

Neither combination of switches creates or destroys money. All that changes is whether the same amount stays "inside the group" or "goes back to the pool". In this example the pool on 1 September works out as follows.

Pool on 1 September = pool at end of August ($0) + August salary ($3,000)
                      + amount returned by Living ($150)
                    = $3,150

Step 4 — Decide the September allocations

On the Allocate Budget screen you enter the total you want each group to have for this period (the target), and the screen works out the new allocation it will actually save by taking the amount already carried over into account. The difference is clearest in a group like Cafe/Snacks whose carryover is negative.

For Cafe/Snacks you simply enter the target you want — "I want a $100 budget in September too" ($100) — and because last month's $30 overspend has to be covered first, the screen works out and saves a new allocation of $130 for you. You never have to do that arithmetic in your head.

Pool on 1 September = 3,150 − 800 − 100 − 130 = $2,120

Checking the arithmetic

The following identity has to hold at both points in time.

total budget value = available pool + amount left in every budget group

• End of August (before closing): pool 3,000 + (150 + 200 − 30) = $3,320.
• 1 September (after closing and reallocating): pool 2,120 + (800 + 300 + 100) = $3,320.

The figures match exactly. Closing the period and reallocating moved money around; it did not create or lose any.

Common misunderstandings

• "My salary is due this month, so I can allocate it now." No. You can only allocate income that has actually been recorded.
• "A negative pool means something is broken." Not always. If the budget period (calendar month) and the payday (the 23rd) do not line up, the pool can look short at the start of a month. Budgeting one month ahead solves it — for example, allocating the 23 August salary to the September budget.
• "Budgets are stored per category." No. A category is only a classification; a budget group is a bundle of categories. Create a new category and leave it unconnected to a budget group, and its spending reduces the whole pool rather than any one group.

On the Allocate Budget screen each budget group name is a section heading, and beneath it the number field with − / + buttons and a slider (amount only, with no separate label) is the target allocation field. The "move between groups" flow described below is a separate screen.

Note — moving an allocation to another group

If you allocated too much to one group, you can move money straight between two groups on the Move Between Groups screen, without going through the pool. The two groups' amounts still add up to the same total before and after the move (a zero-sum move).