The main answers I need from budgeting:

* How much extra money I can spend without compromising ability to pay my bills? 
* How big my earnings should be to cover my expenses?
* How can I optimize my expenses?


## Tracking your expenses
One of my favorite reports `hledger` supports is
```sh
% hledger -f examples/sample.journal bal -Q
Balance changes in 2008:

                      ||  2008q1  2008q2  2008q3  2008q4 
======================++=================================
 assets:bank:checking ||      $1       0       0     $-1 
 assets:bank:saving   ||       0      $1       0       0 
 assets:cash          ||       0     $-2       0       0 
 expenses:food        ||       0      $1       0       0 
 expenses:supplies    ||       0      $1       0       0 
 income:gifts         ||       0     $-1       0       0 
 income:salary        ||     $-1       0       0       0 
 liabilities:debts    ||       0       0       0      $1 
----------------------++---------------------------------
                      ||       0       0       0       0 
```

To limit output only to `expense` just add query:
```sh
% hledger -f examples/sample.journal bal -Q '^expenses'
Balance changes in 2008q2:

                   ||  2008q2 
===================++=========
 expenses:food     ||      $1 
 expenses:supplies ||      $1 
-------------------++---------
                   ||      $2 
```
Now you can see your total expenses and distributed over your accounts.

No need to read further if you this report satisfy your needs.


## Bucketing
Sometimes we don't need such detailed distribution of expenses.
Thanks to `hledger-rewrite` addon we can re-write original journal.
Let's re-distribute our expenses into a buckets of budget by adding virtual extra postings.
```ledger
; examples/budget.journal

= ^expenses:clothes
    (budget:clothes)               *-1

= ^expenses:(food|supplies)
    (budget:grocery)               *-1

= ^expenses: not:^expenses:(clothes|food|supplies)
    (budget:misc)                  *-1

= ^equity:unbalanced
    (budget:unknown)               *-1
```
Now our query looks like this:
```sh
% hledger rewrite -f examples/budget.journal -f examples/sample.journal | hledger -f - bal -Q budget   
Balance changes in 2008q2:

                ||  2008q2 
================++=========
 budget:grocery ||     $-2 
----------------++---------
                ||     $-2 
```
This looks fine but isn't much different from prev section.

## Planning/allocating budget
```ledger
; examples/budget.journal

= ^expenses:clothes
    (budget:clothes)               *-1

= ^expenses:(food|supplies)
    (budget:grocery)               *-1

= ^expenses: not:^expenses:(clothes|food|supplies)
    (budget:misc)                  *-1

= ^equity:unbalanced
    (budget:unknown)               *-1

2008/4/1 Budget for 2008q2
    (budget:clothes)               $10
    (budget:grocery)                $5
    (budget:misc)                   $2
```
This makes our output look like:
```
Balance changes in 2008q2:

                ||  2008q2 
================++=========
 budget:clothes ||     $10 
 budget:grocery ||      $3 
 budget:misc    ||      $2 
----------------++---------
                ||     $15 
```
You can interpret this report like: you still can spend $3 for grocery and $10 for clothes.

## Offset assets according to budget
This helps to identify how much money I left unbudgeted or free for extra expenses.

```ledger
; examples/budget.journal

= ^expenses:clothes
    [budget:clothes]               *-1
    [assets:budget]                *1  ; compensate budgeted expense from assets

= ^expenses:(food|supplies)
    [budget:grocery]               *-1
    [assets:budget]                *1

= ^expenses: not:^expenses:(clothes|food|supplies)
    [budget:misc]                  *-1
    [assets:budget]                *1

= ^equity:unbalanced
    [budget:unknown]               *-1
    [assets:budget]                *1

2008/4/1 Budget for 2008q2
    [assets:budget]  ; subtract budget from assets
    [budget:clothes]               $10
    [budget:grocery]                $5
    [budget:misc]                   $2
```
Now balance for assets looks like this:
```sh
% hledger rewrite -f examples/budget.journal -f examples/sample.journal | hledger -f - bal assets   
                $-16  assets
                  $1    bank:saving
                $-15    budget
                 $-2    cash
--------------------
                $-16
```
This means that our current assets are off by $16 from our budget and current expenses.

## Reset budget
Sometimes we start budgeting later than.
I'd expect that something like this will work:
```ledger
2016/12/31 Budget reset
    assets:budget  = $0
    Budget:Bills  = $0
    Budget:Food  = $0
    Budget:Clothes  = 0 UAH
    Budget:Health  = 0 UAH
    Budget:Medicine  = 0 UAH
```
Be careful to list all accounts. Otherwise your transaction may fail to balance. You can use output of `hledger-budget accounts budget`

## Finally
I've added a simple bash script see `hledger-budget.bash` (drop `.bash` suffix). With year-based includes inside of `~/.hledger-budget.journal`. Be careful about account aliases - they tend to miss budget file.

Since budget will be enabled only during `hledger-budget` I've changed from virtual postings to real ones.