finance-app/docs/expense-baseline.md

Monthly expense baseline and emergency reserve

Analysis run 2026-07-26. One-off analysis, not a feature — nothing in the app computes these numbers. Read "Reproducing this" before trusting a restated figure.

The question: how much should be held in reserve to cover 6–12 months of expenses?

Answer

Scenario	$/mo	6 months	12 months
Survival — contracted loan repayment, essentials only	3,040	18,250	36,500
Realistic — contracted loan, + dining and charity	4,140	24,800	49,600
Status quo — keep overpaying the loan, normal life ex-travel	5,557	33,500	67,000

Use the middle row. The survival row assumes dining is cut to zero and stays there, which is not a plan anyone executes for six months.

Against that, liquidity already available (statements 133 and 131, 2026-06-30):

Loan redraw	81,017.42
Offset balance	8,753.00
Accessible	89,770.42

That is 3.6× the six-month target and 1.8× the twelve-month one. Redraw grew $62,387.17 → $81,017.42 across the last two loan statements, matching the overpayment rate — the money spent killing the loan faster is still reachable.

Caveat on counting redraw as the reserve. It is available at AMP's discretion, and lenders reduce or freeze it exactly when a borrower looks distressed — which is when it would be needed. The rate also moved 5.54% → 6.29% between the two statements, so redrawn funds cost more than they did. Hold some genuine cash; it does not need to be $50,000.

This is your outgoings, not household spend

The app only sees accounts that get imported. Sonu's own spending on the household is invisible to it. Grocery spend reads as ~$300/mo gross on 4–10 transactions, which is implausible for a household and is partly explained by her paying from her own account.

For "how much reserve do I need" that blind spot does not matter — your own outgoings is the correct measure. Do not relabel these figures as household totals; they are not, and they would be wrong by an unknown amount.

The loan has two floors

This is the largest single lever and the reason there are three scenarios.

	$/fortnight	$/mo annualised	Your 50%
Contracted minimum	1,190.54	2,579.50	1,290
Actual direct debit	2,500.00	5,416.67	2,708
Voluntary overpayment	1,309.46	2,837.17	1,419

Dropping to contracted cuts your loan cost by $1,418/mo. Sonu's obligation is a fixed 50% of the repayment (see CLAUDE.md → "The shared loan"), so it falls with it. Her rate returned to $1,250/fortnight in July 2026 after the reduced $750 period during her leave.

Baseline composition

Built from Feb–Jun 2026 — the months where split data is trustworthy — with annual items annualised over 12 rather than divided by the 5-month sample.

Essential	$/mo	Note
Loan (contracted, your 50%)	1,290	2,708 at the current actual rate
Transport	326
Insurance	280	annualised; your 55%
Utilities	278	shared energy/water + personal mobile
Subscriptions	204	shared household + personal/AI
Groceries	200	see the blind-spot note above
Card + package fees	175	annualised — see below
Health	167
Rates + rego	122	annualised, your share
Essential	3,042
+ dining 675, charity 422	4,139	charity is a Smith Family sponsorship commitment
+ typical shopping	~4,800	median 657, not the 1,709 mean

Travel is excluded throughout. At $3,153/mo of your share even post-cutover it would roughly double every figure, and it is the first thing that stops.

Four corrections the raw data needed

Any restatement that skips these will be wrong. None are fixed in the data yet.

Micro-investing counted as spend. Raiz ($9,406 / 27 rows), Vanguard Super ($500) and moomoo ($300) sit in other as debits — $10,206/yr, ~$850/mo of phantom spend. These belong in investment, which is already excluded.

Incoming money counted as negative spend. 17 rows in other typed credit ($5,622 in the window). SPEND_SIGNED negates credits so refunds cancel purchases, but these are not refunds — they are money arriving. June 2025 shows minus $7,814 of total spend because two Wise credits of ~$16.7k each landed in other.

government is two unrelated things. $25,554 of ATO payments (one annual bill, routed through Zen B2B and RewardPay to earn points) versus $2,054 council rates and $875 rego. Tax is not a monthly living cost and falls with income anyway; rates and rego are non-negotiable. Splitting them moves this line from $2,411/mo to $244/mo.

fees is mostly annual. Of $2,599 post-cutover, $1,750 is an annual card fee and $349 a loan package annual fee. Recurring is ~$175/mo annualised, not the $520/mo the 5-month mean implies.

Splits: what is trustworthy and what is not

Splits exist in this app from 2026-01-09 only; before that they were tracked in SplitMyExpenses. So a trailing-12-month per-person series splices six months of gross onto six months of net and is not a series at all. Use Feb–Jun 2026.

Partial split coverage within a category is usually correct, not a gap. This was misdiagnosed once during the analysis. Verified composition:

Category	Your share	Split	Unsplit
utilities	69%	Globird, OVO, GWW, home telecoms	Telstra, Vodafone, Optus, JB Hi-Fi Mobile
subscriptions	91%	Uber One, Amazon Prime, OnePass	Claude, OpenAI, Anthropic, OpenRouter, You.com, LinkedIn, Xero, Billdu, Spotify, Patreon
fees	100%	—	credit card fees are personal
charity	100%	—	personal commitment

Only shared utilities and subscriptions are split. Mobile bills, AI subscriptions and card fees are personal and correctly sit at 100%. Do not "fix" these ratios.

Known weak spots

• other is $424–773/mo of your share and unclassified. The single biggest lever on accuracy. Clearing it with the rule preview (GET /api/rules/[id]/matches) improves every other view at the same time.
• Five months is a short sample, and it contains the Europe trip and the ATO bill. Both are excluded, but they crowd out the ordinary months. The SplitMyExpenses CSVs would stretch it to 18 months — worth having, not blocking, since only an aggregate ratio per category is needed, not row matching, so the combined-transaction problem does not bite.
• /api/analytics/monthly does not filter reconciled_with_id IS NOT NULL. 48 rows are double-counted app-wide. Small, but real, and unrelated to this analysis. The queries below do filter it.

Reproducing this

Working queries are not checked in; they were run ad hoc against postgres-personal. The shape that matters:

-- Per-category monthly distribution, your share, Feb-Jun 2026.
-- Mirrors src/lib/analytics-sql.ts, plus the corrections above.
WITH s AS (
  SELECT to_char(t.transaction_date,'YYYY-MM') m,
    COALESCE(o.category_override, t.category, 'other') cat,
    SUM((CASE WHEN t.transaction_type IN ('refund','credit') THEN -1 ELSE 1 END)
        * (CASE WHEN t.interest_amount IS NOT NULL
                THEN t.interest_amount ELSE COALESCE(t.amount_aud, t.amount) END)
        * COALESCE(ts.share_percent, o.my_share_percent,
            100 - COALESCE((SELECT SUM(x.share_percent) FROM transaction_splits x
                            WHERE x.transaction_id = t.id
                              AND x.participant_id <> 1), 0)) / 100)::numeric(12,2) amt
  FROM transactions t
  LEFT JOIN transaction_overrides o ON o.transaction_id = t.id
  LEFT JOIN transaction_splits ts ON ts.transaction_id = t.id AND ts.participant_id = 1
  LEFT JOIN statements st ON st.id = t.statement_id
  WHERE COALESCE(t.owner_id, st.owner_id) = 1
    AND t.reconciled_with_id IS NULL                      -- see weak spots
    AND ((t.transaction_type IN ('debit','fee','interest')
          OR t.interest_amount IS NOT NULL)
         OR t.transaction_type IN ('refund','credit'))
    AND COALESCE(o.category_override, t.category, 'other')
        NOT IN ('transfers','investment','income')
    -- correction 1: misfiled investments
    AND COALESCE(t.merchant_normalized, t.merchant_name, '')
        !~* '^(Raiz|Vanguard Super|moomoo)'
    -- correction 2: incoming money miscategorised as 'other' credits
    AND NOT (COALESCE(o.category_override, t.category, 'other') = 'other'
             AND t.transaction_type = 'credit')
    AND t.transaction_date >= '2026-02-01' AND t.transaction_date < '2026-07-01'
  GROUP BY 1, 2
)
SELECT cat, count(*) mths, round(avg(amt),0) mean,
       round(percentile_cont(0.5) WITHIN GROUP (ORDER BY amt)::numeric, 0) median
FROM s GROUP BY cat ORDER BY mean DESC;

Use the median for anything recurring monthly and the annualised total for lumpy-but-certain items (insurance, rates, rego, annual card fees). Means are badly skewed here — shopping is 1,709 mean against 657 median.

Corrections 3 and 4 (government, fees) are not expressible as filters; they need the category split by merchant, done by hand above.

If this becomes a feature

The blocker is other, not the split model — the split data held up under scrutiny. Sequence:

1. Recategorise Raiz / Vanguard Super / moomoo to investment (27 rows, unambiguous) via the rule preview.
2. Split government so rates and rego separate from ATO. Probably a new category or a tag; government conflates a recurring obligation with an annual tax bill.
3. Work other down with the rule preview.
4. Then a baseline panel on Insights, which already carries the Regular/Occasional split this analysis is a stricter version of (REGULAR_CATEGORIES in src/lib/categories.ts).

A liquidity vs baseline view would be genuinely new rather than a restatement: statements.redraw_available, offset closing balance, and the contracted-vs-actual repayment gap are all in the schema and nothing reads them.