nest-math

# Nest Math

A goal with no number and no date cannot be planned. Size the nest. Glide as the date nears.

Inspired by kusandriadi/finance financial-planning.md (MIT). Original Grok remake. Country-neutral. Complements cash-plan (this month's cashflow), invest-map (accumulation allocation), cover-map (insurance), roof-math (housing), heir-check (beneficiaries). Not a pension product.

Read `references/rails.md` before you write numbers. Fill the three templates.

## When to use
- FIRE, 4 percent rule, how much to retire, retirement number
- Savings rate vs return, spend floor, nest size
- Glide toward safer assets as the date nears
- They already have cashflow and cover named and now want a long-horizon nest worksheet

## When NOT to use
- This-month budget (use cash-plan)
- First portfolio / DCA / index allocation (use invest-map)
- Rent vs buy / mortgage (use roof-math)
- Insurance map (use cover-map)
- Beneficiaries (use heir-check)
- Brokerage APIs, options/futures trading, tax-filing, legal drafting

## Inputs
- Country / currency context (keep products generic if unknown)
- Annual spend floor they want later, in today's money
- Target date or years until work is optional
- Current nest (long-term savings they would actually use) if known
- Savings rate as a % of take-home, or a monthly save amount
- Age, plus a plain-words temperament (sleep-at-night drawdown)
- Emergency cash (months of needs) and high-interest debt status

## Procedure
1. Read `references/rails.md`. Refuse brokerage APIs, trade tickets, account logins, and tax-filing software.
2. Gate with the pyramid. Do not skip the foundation to chase return. Order: positive cashflow, then high-interest consumer debt, then emergency fund, then protection (health / life), then medium goals, then long-term / retirement, then later tax / estate polish. Send to cash-plan or cover-map if the gate fails. Nest-math does not invent a budget or a policy.
3. Name the goal in three parts: for what, how much, by when. Fill `templates/goal-horizon.md`.
4. Horizon picks the risk. Under ~2 years stay in cash-like. 2-5 years mixed / safer income. 5-10+ years can hold more growth assets because time absorbs volatility. Do not put a near-term goal in stocks.
5. Spend floor first. Nest sketch = annual spend / withdrawal sketch. 4% / 25x annual spend is a historical US-market sketch, not a law. Many planners use ~3-3.5% (about 28-33x) as a more cautious sketch. Label it a sketch. Inflation means today's "enough" is not 10-year enough.
6. FIRE frame if they ask: save 25-33x annual spend, then live off the portfolio sketch. The big lever is savings RATE, not return. A 50% save rate changes the calendar more than a 2% extra return. Start early because compounding needs time more than a huge first deposit.
7. Quantify when they give numbers. Years of saving from rate. State assumptions so they can sanity-check. Fill `templates/nest-number.md`.
8. Starting equity share ~ (100 - age)% as a guess, then slide for risk capacity vs temperament. The smaller of the two binds. Glide: shift toward safer assets as the date nears to lock results. Fill `templates/glide.md`. Point accumulation detail to invest-map (no tickers). Point housing to roof-math. Point named heirs to heir-check.
9. Name common errors. Confirm locally. Their call.

## Output format
- Goal-horizon card (what, how much, by when, band)
- Nest-number card (spend floor, 25-33x sketch, savings-rate lever)
- Glide card (equity guess, temperament vs capacity, shift as the date nears)
- One line: education worksheet; not financial advice

## Safety
- Follow `references/rails.md` with no exceptions.
- No brokerage, no trade tickets, no account logins, no tax-filing software.
- No return promises. Label 25-33x as a sketch.
- Country-neutral: no Indonesia-only products (RDPU, SBN, KPR, zakat, and similar) as requirements.
- Their call. Not a pension product.

## Stop conditions
- Three templates delivered, or refused because they need a licensed advisor / tax pro / cash-plan first, or they asked for brokerage APIs or trade placement