Regarding Optional vs. Necessary: I tend to agree with Arebelspy, but on another hand, I think about it this way: If I decided to do "nothing" what would I be absolutely mandated to pay for?
Here's our budget now:
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$000-- Paid off house
$230-- Utilities
$200-- Food & Dining
$150-- Gasoline
$106-- Property Tax
$76-- Personal Care/Diapers
$70-- Household Supplies
$58-- Auto Insurance
$46-- Home Insurance
$42-- Clothing
$30-- Auto maintenance
$22-- Internet
$20-- Birthday Presents
$20-- Fun Activities
$17-- Life Insurance
$15-- Education Supplies
$10-- Home Phone
$10-- Vision/Glasses
$9-- Auto License/Registration
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$1121-- Total Monthly Budget
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If we decided to do "nothing"--- i.e., voluntary state of financial emergency (I quit my job and refuse to look for another one, but am otherwise able-bodied), we could cut out some things, while others we could not (at least, not without doing something equally drastic like selling the house. Which would be dumb, because we can't rent or camp anywhere nearly as cheaply).
Here's what a financial emergency budget would look like:
$000-- Paid off house
$230-- Utilities
$150-- Food & Dining
$150-- Gasoline We wouldn't drive anywhere, and resort to bicycling.
$106-- Property Tax
$76-- Personal Care/Diapers
$70 $50-- Household Supplies This would be reined in by about half.
$58-- Auto Insurance Gone.
$46-- Home Insurance
$42 $20-- Clothing Halved, and likely we wouldn't spend this amount, except to replace clothes outgrown by the kiddos.
$30-- Auto maintenance Gone.
$22-- Internet We'd use the (free) internet access at the library
$20-- Birthday Presents Gone.
$20-- Fun Activities Gone.
$17-- Life Insurance I'd consider letting this lapse, but I think it'd be prudent to keep it.
$15-- Education Supplies
$10-- Home Phone We'd go to all email/social media, and look into snagging a free service like Freedompop.
$10-- Vision/Glasses
$9-- Auto License/Registration Gone.
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$720-- Total Monthly Budget
So our "optional" spending is ~$400. We do sometimes spend on other optional things (like ice creams at Costco yesterday), but I don't count them because (1) they're not often, and (2) they're funded by optional income (I sell a batch of cookies or something), and if there was no money for them, we wouldn't be any less happy or miss it at all.