If income is $40K the tax is $3488
This means the total tax % is 8%
There is no tax advantage to salary sacrifice more concessional super in addition to employers contribution. as concessional super as concessional contributions are taxed at 15% at entry.
The spouse split is taxed via your super account first before it is split.
Plus 2% med levy. Less the LITO.
Copied from Superguide...
"earn $37,500 or less you’ll get the full LITO of $700. This amount reduces by 5 cents for each dollar earned over $37,500, and then by 1.5 cents for every dollar over $45,000" and
"The $700 Low Income Tax Offset (LITO), combined with the tax-free threshold of $18,200, effectively allows working Australians to earn up to $22,575 for the 2025-26 financial year before they need to pay any income tax. Medicare Levy is not payable until a taxpayer has annual income of $26,000 or more"
So, having contributed an intended non-concessional amount before 30 June, a plan might be for her to complete (but not lodge) her 25/26 return, then put in the "Notice of intent to claim... a deduction..." form for that portion of the non-concessional contribution made which will get her income down to $26k ; get acknowledgement, claim deduction, lodge. Concessional contribution limit, inc employer, shouldn't be an issue at original income indicated.
Small bikkies (3% saving) but very little effort (less than my typing this) as the contribution has already been made; fill out a form, then a few clicks on computer if diy tax return after you get acknowledgement.
Just a thought, I'm not an accountant, I've probably missed something, never follow advice from social media.