Day one after the split.

Income. Her pay starts at $51,000 and rises with CPI every year (3.5%), plus one promotion, a 10% increase, applied from year 5 onward on top of the CPI-adjusted figure. The 10% figure draws on general compensation research suggesting promotional increases typically run higher than ordinary annual pay rises (which average 3 to 5% a year in Australia per AIM and Mercer survey data), though no Australia specific figure for promotion sized increases was found, so this is the least firmly sourced number in the model. His pay gets no separate CPI adjustment, since his career growth curve (reaching roughly 4x his starting salary by 50) already climbs well ahead of inflation on its own. Tax uses 2024-25 Australian resident rates plus the 2% Medicare levy.

Household expenses and costs. Her rent starts at $850/week, the real median Sydney house rent in 2026 (Domain/CoreLogic), rising 5.5% a year, the current reported annual growth rate for Sydney house rents specifically (re-accelerating through 2026 after a brief mid-2025 cooling; most forecasters expect this to ease toward 3 to 5% in future years, but 5.5% reflects what is actually being reported right now). Her other living costs (groceries, utilities, everything outside rent) are built bottom-up rather than picked as a round number. Her own adult cost of living is $548 a week (Sydney 2026, Domain/Finder/ABS/Transport NSW/AER sourced). Each child's cost is added on top using University of Canberra/NATSEM "Cost of Kids" research for a middle income family, by age band ($133/week at 0-4, $198 at 5-9, $228 at 10-14, $414 at 15-17), with the roughly 13% of that figure attributed to housing stripped out, since rent is already counted separately above. The whole total then rises with CPI, 3.5% a year (the ABS trimmed mean, the RBA's preferred underlying inflation measure, which has held between 3.3% and 3.6% through 2026). The result isn't a smooth line: it steps up when a child crosses into the next age band, which is what the real research shows actually happens, most sharply when the older child turns 15. His mortgage is a real 30 year loan at 5.90% (the current RBA average owner occupier rate), properly amortised month by month, not averaged. His other household expenses are set at 30% of his net income (so they rise as his pay does, rather than staying fixed), and his savings/investing at a further 20%, based on the widely used 50/30/20 budgeting benchmark (there is no single official figure for what high income earners specifically save, though research confirms they typically save well above the roughly 10% average Australian savings rate). Of his savings, 80% goes to shares/managed funds and 20% to cash; that 80/20 split is a reasoned estimate, not a sourced statistic (ABS data shows the average Australian household puts most new savings into deposits, 61.2%, and relatively little into shares, 10.2%, but that average mixes every income level and mostly reflects a liquidity buffer that does not need to keep growing just because income does, so it is not the right benchmark for a high earner's surplus). Car is locked at $55,000 flat each, for both of them.

Child support. Uses the real 2024 Services Australia Costs of the Children Table (self support amount $28,463, stepped rates, capped at $40,561 a year for 2 children once combined income passes about $213,000, however much higher it climbs after that), applied with a standard alternate weekend care assumption (24% cost share to him). One simplification kept for now: the costs table used is for two children both under 13, even once the older child turns 13 around year 8.

Settlement, day one. The family home is sold at separation, the mortgage is paid off, and the remaining equity is pooled with their shares and cash, then split 55/45. He uses his full settlement payout ($228,000 cash and shares) as a 20% deposit and buys a $1,140,000 home with a $912,000 loan straight after separation, a loan size that lines up with what his year one income can service at standard lending multiples, so his house equity line going forward reflects what he has actually paid off, not just the house's rising value. She continues renting throughout; no purchase is modelled for her in this version.