Quick answer
The ATO days calculator counts calendar days between two dates. That suits tests like the CGT 12-month rule, but many deadlines don't work that way. Under federal law, a period running from a date usually starts the next day, and a last day on a weekend or holiday moves to the next business day. Payday Super and ATO payment processing count business days.
Key points
- The ATO's Calculate days tool counts calendar days only. For the CGT 12-month test, the ATO says to leave out both the day you acquired the asset and the day of the CGT event.
- Under section 36 of the Acts Interpretation Act 1901, a period that runs from or after a day doesn't include that day, so day one is the day after.
- If the last day of a period set by a Commonwealth Act is a Saturday, Sunday or holiday, it can be done on the next day that isn't.
- Count a notice period from the date on the notice, not the day you opened it.
- The ATO says BPAY payments can take up to 4 business days to reach it, so the payment date and the due date are different days.
- Payday Super is counted in business days: 7 after payday, or 20 for a new employee or a fund change.
The ATO days calculator counts calendar days between two dates, weekends and holidays included. That suits a test like the CGT 12-month rule, but most deadlines that matter to your cash don’t work that way. Under federal law, a period that runs from a date usually starts the next day, and a last day that lands on a weekend or holiday moves to the next business day. Payday Super and ATO payment processing count business days.
So the calculator gives you a number. Your deadline is a date, and getting to it takes three more questions: which day is day 1, what kind of days you’re counting, and when the money has to arrive.
What the ATO days calculator actually does
The ATO’s Calculate days tool takes two dates and tells you how many days sit between them. That’s it. It doesn’t know about public holidays, business days or which state you’re in.
The ATO pitches it at two jobs. The first is the capital gains tax 12-month test, and the ATO’s own instructions say to leave out both the day you acquired the asset and the day of the CGT event. The second is counting how many days have passed since you lodged something.
Both are calendar-day questions, and the tool handles them well. The trouble starts when people use it for deadlines it wasn’t built for.
Calendar days vs business days: which does your deadline use?
Here’s a quick sorter. Find your deadline, then pick the right counter.
| Deadline | What you count | Use |
|---|---|---|
| CGT 12-month discount test | Calendar days, leaving out the acquisition day and the CGT event day | ATO Calculate days |
| “Within 21 days” or “28 days from the date of this notice” | Calendar days, from the day after the notice date | Calendar, then check the last day |
| BAS, IAS and other fixed due dates | A fixed date, moved if it falls on a weekend or holiday | The ATO due date list |
| Payday Super | 7 business days after payday (20 for a new employee or fund change) | Business day counter |
| Getting a payment to the ATO | Up to 4 business days for BPAY | Business day counter, counting backwards |
| Supplier or contract terms | Whatever the document says (often calendar days for “net 30”, business days for notices) | Read the clause first |
If you’re not sure whether something is a business day in your state, our guide to what counts as a business day in Australia covers the three versions in use.
Rule 1: day 1 is usually the day after
The Acts Interpretation Act 1901 sets the default for Commonwealth laws. Section 36 says a period that begins from or after a day doesn’t include that day. So “within 28 days after the date of the notice” starts counting the following morning.
That’s why the ATO tool’s CGT instructions tell you to strip out the starting day. A plain “days between” figure from any calculator can be off by one depending on whether it counts the first day, the last day, both or neither.
A quick way to check yourself: if a notice is dated the 1st and you have 28 days, your last day is the 29th. If your answer is the 28th, you’ve counted the start day.
Rule 2: count from the date on the notice, not the day you read it
This is the mistake that actually costs people. A letter dated Monday 26 October 2026 might reach your post box on Thursday 29 October, or sit in a myGov inbox until you log in the following week. The clock started on the date of the notice.
| Counting from the notice date | Counting from the day you opened it | |
|---|---|---|
| Start | Monday 26 October 2026 | Thursday 29 October 2026 |
| Day 1 | Tuesday 27 October | Friday 30 October |
| Day 28 | Monday 23 November | Thursday 26 November |
Counting the second way puts you three days late without noticing. If the notice prints its own due date, use that date. If it only gives a number of days, count from the date at the top of the page.
Rule 3: when the last day is a weekend or holiday
Section 36 of the same Act says that when the last day of a period set by a Commonwealth Act is a Saturday, a Sunday or a holiday, you can do the thing on the next day that isn’t. The ATO applies the same approach to lodgment and payment due dates, and it counts a public holiday observed across the whole of any state.
December shows how far that can move a date. Take an illustrative notice dated Friday 4 December 2026 with 21 days to respond:
- Day 1 is Saturday 5 December.
- Day 21 is Friday 25 December, Christmas Day.
- Saturday 26 and Sunday 27 are weekend days, and Monday 28 December is the Boxing Day public holiday.
- The last day becomes Tuesday 29 December.
That extra time helps on paper, but don’t plan around it. Many offices, bookkeepers and lenders are on leave that week, so treat Thursday 24 December as your real deadline. Our 2026–27 public holidays cash calendar marks the dates that shift things.
Rule 4: a payment counts when the ATO receives it
The ATO says BPAY payments can take up to 4 business days to reach it and appear on your account. A payment counts when the ATO receives it, not when you press “pay”. So for any ATO amount, there are two dates: the due date, and the last day you can send the money.
Work it backwards in business days. For an illustrative March-quarter BAS due Wednesday 28 April 2027 in NSW:
| Business day before the due date | Date |
|---|---|
| 4th | Tuesday 27 April |
| (Anzac Day public holiday, NSW) | Monday 26 April, skipped |
| 3rd | Friday 23 April |
| 2nd | Thursday 22 April |
| 1st | Wednesday 21 April: pay by today |
Anzac Day falls on a Sunday in 2027, so NSW gets Monday 26 April off and that pushes the safe payment date back a day. Victoria doesn’t take the Monday, so a Melbourne business could pay on Thursday 22 April. Faster methods may land sooner, and our guide to PayID, Osko and how fast payments arrive explains which ones. But “up to 4 business days” is the figure the ATO publishes, so it’s the one to plan around.
If the money for that payment won’t be in the account by your send date, it’s worth checking your options now, while you still have business days to work with.
Rule 5: Payday Super runs on business days
From 1 July 2026, super has to reach the employee’s fund within 7 business days of payday, or 20 business days for a new employee or one who has changed funds. Payday itself isn’t counted, and neither is a day that’s a statewide holiday in any state.
Over Christmas, calendar-day maths gets this badly wrong. For an illustrative Thursday 24 December 2026 payday:
- Counting 7 calendar days gives Thursday 31 December.
- Counting 7 business days skips Christmas Day, the weekend, the Boxing Day holiday, New Year’s Day and the next weekend, and lands on Thursday 7 January 2027.
Here the calendar count is a week early, which is safe. Other mistakes run the other way, so count it properly every time. If super is due this week and the cash is short, our page on super due this week walks through the options.
What date is 10 business days from today?
People search for this one constantly, so here it is for the day this guide went up. From Friday 23 October 2026:
- Most states and territories: Friday 6 November 2026.
- Victoria: Monday 9 November 2026, because Melbourne Cup Day (Tuesday 3 November) isn’t a business day there.
For any other start date, state or number of days, the business day counter does it in a couple of seconds and shows which days it skipped.
The five-minute routine for any ATO date
Next time a letter or a due date lands, run through this before you put it in the diary:
- Find the start date. Use the date on the notice or the date of the event, not the day you saw it.
- Check the type of days. Calendar days unless the document says “business days”.
- Count from the day after. Day 1 is the morning after the start date.
- Check the last day. If it’s a Saturday, Sunday or public holiday, note the next business day, but plan to the earlier date.
- Work back the payment date. If money has to reach the ATO, count back up to 4 business days and diarise that as the deadline.
- Look at the account. Open your bank balance against the send date, not the due date. If a BAS is due tomorrow and the money isn’t there, BAS due tomorrow covers what you can do tonight.
Step six is where most “due tomorrow” situations start. The count was right, but the cash wasn’t lined up for the earlier send date.
When the count shows the money won’t be there in time
Counting the days properly tells you something useful. Often it’s good news and you have more room than you thought. Sometimes it shows the ATO payment, a Payday Super run and a supplier bill all need to go out in the same short week, and the account won’t cover all three.
That’s a gap we see all the time, and it’s much easier to fix with a few business days in hand than on the last afternoon. Property-secured funding from $20k to $5m and unsecured options for trading businesses can sometimes be arranged by the next business day, though speed is never guaranteed.
The enquiry takes about 60 seconds, and your credit file stays untouched just for asking. We don’t send your details to a pile of lenders, so you won’t spend next week fielding calls from strangers. A real person reads your enquiry, looks at your situation and calls you. Please fill it in accurately, especially the amount, the date the ATO needs the money and your state. Those three details decide which options fit and how many business days we have to work with.
Frequently asked questions
Does the ATO days calculator count business days?
No. The ATO's Calculate days tool counts calendar days between two dates, weekends and public holidays included. Use it for calendar-day tests such as the CGT 12-month rule. For Payday Super, ATO payment processing time or anything written in business days, use a business day counter that skips weekends and public holidays.
How do I count 28 days from the date of a notice?
Start counting the day after the date printed on the notice, and day 28 is your last day. A notice dated Monday 26 October 2026 gives a 28th day of Monday 23 November 2026. Count from the notice date, not the day the letter arrived or the day you opened it. If the notice prints its own due date, that date is the one to use.
Does the first day count when counting days?
Usually not. Under section 36 of the Acts Interpretation Act 1901, a period that begins from or after a given day doesn't include that day. So for 21 days after a notice, the day after the notice is day 1. Contracts can set their own rule, so check the wording if the deadline is in an agreement rather than a law.
What if the 28th day falls on a weekend or public holiday?
For deadlines set by Commonwealth law, section 36 lets you do the thing on the next day that isn't a Saturday, Sunday or holiday. The ATO applies the same idea to lodgment and payment due dates. A deadline on Christmas Day 2026, a Friday, rolls past the weekend and the Boxing Day holiday to Tuesday 29 December.
What date is 10 business days from today?
From Friday 23 October 2026, 10 business days in most states takes you to Friday 6 November 2026. In Victoria it's Monday 9 November, because Melbourne Cup Day on Tuesday 3 November isn't a business day there. Our business day counter works this out for any state and start date.
How many days before the due date should I pay the ATO?
The ATO says BPAY payments can take up to 4 business days to reach it and show on your account, and a payment only counts once it's received. So count 4 business days back from the due date, and allow for any public holiday in between. For a BAS due Wednesday 28 April 2027, that means paying by Wednesday 21 April in NSW.
Can I borrow to pay the ATO on time?
Yes. Paying a tax debt or BAS on time is a legitimate business purpose, and many trading businesses use short-term funding or a standby line of credit to cover it. The sooner you ask, the more business days you keep, and an enquiry won't touch your credit file.