Build your sole trader reserve rule
Start with the payment pattern that actually hits your bank. Buffer turns it into a reserve rule, but it also asks for the tax facts that materially change HELP, Medicare levy, MLS, GST credits, and deductible super.
On $4,500 in — reserve $297 immediately — $2,703 is yours. Assumes payments of $4,500 usually arrive monthly.
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$297
Per incoming payment
Business costs
$1,500
Estimated per cycle
Owner pay
$2,703
After costs + reserves
Quarterly target
$892
Monthly reserve
$297
The reserve rule is only as good as these tax bases
Four figures that drive everything: taxable income, HELP income, MLS income, and GST registration status.
Taxable income
Used for income tax and Medicare levy.
HELP repayment income
Includes deductible super when relevant.
MLS income
Used for surcharge testing.
GST status
GST is excluded from the reserve unless you choose to model registration.
Important conditions behind this estimate
- —Uses single-person Medicare levy and MLS settings.
Set cashflow, then add the legal details that change tax.
Accuracy-first: asks for facts that materially change Medicare levy, MLS, HELP, GST credits, and deductible super.
Quick presets
Cash coming in
Define the recurring pattern
Planning shortcut, not a turnover test in legislation.
If GST registered, use GST-inclusive amounts and set the credit method below.
Tax profile
Affects HELP, Medicare, MLS
GST treatment
Net GST depends on credits
Super reserve
Cash bucket + deduction setting
See exactly where the reserve goes.
Shows all major cash and tax components explicitly — the gap between the reserve ratio and owner pay.
Monthly reserve
$297
Monthly owner pay
$2,703
GST credits assumed
$0
HELP income base
$36,000
- —Assumes payments of $4,500 usually arrive monthly.
- —Estimated business costs of $18,000 are deducted before owner pay is shown.
Use the reserve rule inside the rest of your workflow
The next tool depends on whether you need BAS detail, annual modelling, or the next due date.
Go to BAS calculator
Check GST and PAYG statement-style detail after deciding how much to reserve.
Open annual tax calculator
Move from a reserve habit into broader yearly modelling when you need deeper planning.
Check due dates
Line the reserve rule up with BAS, super, and lodgment timing once the cash system is set.
Pick the next action based on what is still unclear
These routes keep the reserve rule in context instead of forcing every sole trader question through one calculator.
Need the habit and account setup?
Open the operating guide when the number is clear but the weekly routine still is not.
Need statement-style BAS detail?
Move into BAS when the reserve rule is done and the next question is GST or PAYG reporting detail.
Need the next deadline?
Open the tax calendar when timing matters more than annual modelling.
Frequently asked questions
What is a tax buffer for sole traders?
How much should a sole trader set aside for tax?
Does this calculator include GST?
Should I include super in my tax buffer?
How often should I transfer money to my tax buffer?
Tax Accuracy & Sources
Estimates a sole trader tax and GST reserve rule based on annualised income patterns. Does not constitute tax advice. Actual tax obligations depend on full-year income, deductions, and ATO assessments.