How it works

SeparationSense is built from deterministic “engines” — every dollar comes from the published rules, not guesswork. Here’s the plain-English version of what’s happening under the hood.

1. Child support

We use the Australian child support formula (Formula 1). In short: each parent’s income, minus a self-support amount, gives their “child support income”. We combine them, work out each parent’s share, then compare it to the share of care each parent provides (based on nights per fortnight). The difference, applied to the legislated cost of raising the children, decides who pays whom and how much. Selling the house doesn’t change this directly — child support is income-and-care based, not asset based.

2. Each household’s cashflow

One household becomes two. For each, we add up after-tax income, child support flowing in or out, and government support, then subtract housing, living costs and debts. The headline is simple: can each household cover itself? Take-home pay is estimated using FY 2025–26 resident tax rates, the Medicare levy and the Low Income Tax Offset.

3. Government support

We estimate Family Tax Benefit Parts A and B, Parenting Payment (single) and Rent Assistance, based on income and care. The important interaction most tools miss: the Maintenance Income Test — child support you receive reduces your Family Tax Benefit Part A above a threshold, down to the base rate. That’s a common, nasty surprise, and SeparationSense models it for you.

4. What-if & scenarios

Change any input and everything recalculates instantly. You can save scenarios and compare them side by side — for example, your situation now versus 50/50 care, or before versus after a pay rise.