it is incredibly accurate - IF you're starting with a clean slate - so no reductions to ftb due to previous underestimates, no changes to child support assessments that may have left you overpaid anywhere and your payments reduced

it will only pay that much once you've proven rental amount - so you can use it as an estimate for the RE, but if they want proof, it's not possible to provide

i guess you also have to keep in mind that it estimates child support - so you have to assume you're going to receive that - your FTB will be impacted whether he pays or not, so if there is even the teeniest bit of doubt he'll pay, work your budget on him NOT paying, and your ftb still being reduced - if you can comfortably pay the rent on that, then you're smooth sailing

keep in mind ANY change to child support (increase) can result in your ENTIRE year being reassessed and may result in reductions to your ftb for the balance of the financial year.