GIC & SIC No Longer Deductible: What It Costs Gold Coast Businesses Now

Most Gold Coast business owners know that paying tax late comes with a cost. But here's what a lot of people still haven't registered: from 1 July 2025, that cost just got a lot heavier. The ATO's interest charges — the General Interest Charge (GIC) and the Shortfall Interest Charge (SIC) — are no longer tax-deductible. Not even partially. Not even if the debt relates to an earlier income year.

It's a quiet change that slipped under the radar for many businesses. But the financial impact is anything but quiet. If you've ever relied on the fact that ATO interest was at least partially offset by a tax deduction, that buffer is gone — and the real cost of falling behind on your tax obligations has jumped significantly overnight.

What Are GIC and SIC — And Why Did They Matter?

Let's start with the basics, because these two charges are commonly confused — or lumped together without much thought.

General Interest Charge (GIC)

The GIC is what the ATO charges when a tax debt isn't paid by its due date. It compounds daily and is recalculated each quarter. Historically, the GIC rate has hovered around 11–12% per annum — well above most commercial lending rates. It applies to unpaid income tax, GST, PAYG withholding, super guarantee charges, and other tax obligations.

Shortfall Interest Charge (SIC)

The SIC is a bit different. It kicks in when an income tax assessment is amended — typically following an audit or a voluntary amendment — and the result is an increased tax liability. Instead of applying the full GIC rate, the ATO applies SIC to the shortfall for the period between when the tax should originally have been paid and when the amended assessment is issued. The SIC rate is generally lower than GIC, but it can accumulate significantly when the underlying shortfall is large or the period is long.

What Changed on 1 July 2025

Before this date, both GIC and SIC were treated as deductible business expenses. If your company incurred $10,000 in GIC, you could claim it as a deduction — reducing your taxable income and giving you back roughly $2,500 in tax (at the 25% company rate). It didn't make the interest painless, but it softened the blow. That offset is now completely gone.

What Does This Actually Cost in Real Dollars?

Let's make this concrete. Say your business owes $80,000 in income tax and — due to a cash flow crunch — you're six months late paying it. At a GIC rate of 11.5% per annum, the interest bill for that six months is approximately $4,600.

Under the old rules, a company in the 25% tax bracket would have received a $1,150 tax deduction benefit on that $4,600 — reducing the effective after-tax cost to around $3,450. Under the new rules, you're paying the full $4,600 with absolutely no offset. That's a 33% increase in the real cost of being late.

And it compounds daily. A debt that sits unpaid for 12 months doesn't just accumulate one year of interest — the interest itself accrues interest. For businesses carrying significant tax debts, this can escalate quickly into a serious financial problem.

Who Does This Affect? More People Than You'd Think

A lot of business owners read something like this and assume it only applies to people who deliberately avoid paying tax. That's not true at all. GIC and SIC arise in a wide range of completely ordinary business situations — including ones where there's no intentional wrongdoing involved.

Cash Flow Difficulties

The most common scenario: a business hits a rough patch — a slow season, a large debtor who doesn't pay, an unexpected expense — and simply can't meet a tax payment deadline on time. GIC kicks in from day one after the due date. For Gold Coast businesses in tourism, construction, and hospitality, seasonal cash flow gaps are a genuine and recurring reality.

ATO Audits and Amended Assessments

If the ATO reviews your return and determines you've underpaid — even if it's a genuine difference of interpretation rather than deliberate underreporting — the SIC applies to the shortfall from the original due date. You may not have known there was a problem, but the interest clock has been running the whole time.

BAS Errors Corrected Later

GST errors happen. Coding mistakes, missed invoices, incorrect input tax credit claims — these are common bookkeeping issues that are often picked up and corrected through an amended BAS. When corrections result in an increased liability, GIC applies to the period the tax was outstanding.

PAYG Instalment Underestimates

If you significantly underestimate your PAYG instalments throughout the year and end up with a large tax bill at lodgement, penalties and interest can apply to the shortfall between what you should have been paying and what you actually paid.

The Bigger Picture: The ATO Is Tightening the True Cost of Non-Compliance

This change doesn't exist in isolation. It's part of a broader shift in how the ATO approaches compliance — one where the financial consequences of falling behind are becoming progressively more severe.

Combine the removal of GIC and SIC deductibility with the ATO's expanded data-matching capabilities in 2026, and the message is unmistakeable: the system is being redesigned to make proactive compliance the only financially rational choice. Reactive compliance — dealing with issues after they're flagged — is now significantly more expensive than it used to be.

"Paying tax late used to sting. From July 2025, it stings a lot more — and there's no deduction to soften it. The smartest thing any Gold Coast business can do right now is treat every tax deadline like the full cost is on them. Because it is."

— Homemax Accounting Team

Five Practical Steps to Protect Your Business Right Now

What If You're Already Carrying a Tax Debt?

If your business currently has an outstanding tax debt with the ATO — or if you're aware of an issue that might result in an amended assessment — the most important thing you can do is act now.

Every day a debt sits unresolved, GIC is accruing. And from 1 July 2025, none of that interest is giving you anything back at tax time. The longer you wait, the higher the net cost — with no tax relief to cushion it.

A Quick Reference: GIC vs SIC at a Glance

Feature	General Interest Charge (GIC)	Shortfall Interest Charge (SIC)
When it applies	Tax debt not paid by due date	Amended assessment results in increased liability
Rate (approx.)	~11–12% per annum	Lower than GIC (set quarterly by ATO)
Compounds	Daily	Daily
Who it affects	All taxpayers with unpaid debts	Taxpayers with amended income tax assessments
Tax deductible from 1 July 2025?	❌ No	❌ No

The Bottom Line

This isn't a change that's coming — it's already here. If your business has incurred GIC or SIC at any point since 1 July 2025, those charges are sitting on your books as a full, non-deductible cost. There's no longer a silver lining in the form of a tax deduction.

The message from the ATO is clear: staying current with your obligations isn't just good practice — it's now significantly cheaper than falling behind. And for Gold Coast businesses navigating an already-tight operating environment, that's a gap worth closing as quickly as possible.

At Homemax Accounting, we help clients stay ahead of their ATO obligations all year round — not just at lodgement time. Whether it's keeping your PAYG instalments accurate, reviewing your BAS before it goes out, or working through a current debt situation, our team is here to make sure you're never paying more than you should.