Can't Access the BAS Portal? Here's What Actually Works

You're locked out of the BAS portal, the lodgement deadline is today, and you've already tried logging in three times. This guide covers the three most common access failures that actually stop BAS lodgements, the immediate fixes that work, and your backup options when the portal simply won't cooperate.

Why the BAS Portal Locks You Out at the Worst Possible Time

It's 4pm on lodgement day. You've got your figures ready, you click through to the BAS portal, and nothing happens. Or worse, you get halfway through entering data and the system boots you out.

Portal access issues spike during quarter-end periods when ATO systems are under heavy load. Authentication changes rolled out through 2025 and into 2026 have made credential issues more common, particularly for businesses that migrated from AUSkey to the new myGovID and Relationship Authorisation Manager (RAM) system. The technical reason matters less than the fix, so let's identify what's actually stopping you.

The Three Access Failures That Actually Stop Lodgements

Most BAS portal lockouts in 2026 fall into three categories. Work out which one you're experiencing, then jump to the relevant fix below.

myGov authentication loops that never complete

You log into myGov successfully. You click through to the ATO. Then you're bounced straight back to the myGov login screen. You try again. Same result.

This is caused by cached credentials or session conflicts between myGov and ATO systems. It affects both individual practitioners and those accessing business portals through myGov. The systems can't complete the authentication handshake, so they keep passing you back and forth.

AUSkey/ABR credential mismatches after the 2025 migration

You can log in fine. But when you try to access your BAS, you get 'not authorised' or 'ABN not linked' errors.

The 2025 migration from AUSkey to myGovID and RAM created linking issues for many business accounts. Your credentials work, but the system can't connect them to your ABN properly. This particularly affects businesses with multiple ABNs or those who changed their access arrangements during the migration period.

Browser session timeouts that wipe half-completed BAS forms

You're partway through entering your BAS data. You switch to your accounting software to check a figure. When you return to the portal, you're logged out and your work is gone.

Portal sessions timeout after 30 minutes of inactivity. The problem? Typing in form fields doesn't count as activity. If you're gathering figures from multiple sources while the portal sits open, you'll hit the timeout without realising it.

What to Do Right Now If You're Locked Out

Match your problem to the steps below. These are tested fixes that resolve most access issues.

For myGov loops: The cache-and-credential reset sequence

Follow this exact sequence:

1. Log out of both myGov and the ATO completely

2. Clear your browser cache and cookies for both sites

3. Close all browser windows

4. Wait five minutes

5. Log back into myGov first, then navigate to the ATO from there

If that doesn't work, try a different browser or use incognito/private mode. This forces a fresh authentication handshake between the two systems. It's simple, but it works for most loop issues.

For credential errors: Verifying your ABN link in Access Manager

Access Relationship Authorisation Manager (RAM) through your myGovID login. Check that your ABN is properly linked and that you have 'Lodge BAS' permissions listed.

If the ABN isn't showing or permissions are missing, you need to request access from the business's principal authority. This is usually the business owner or director who controls access permissions. Permission changes can take 24 hours to propagate through ATO systems, so request this immediately if you're close to a deadline.

For session timeouts: The offline draft workaround

Prepare your BAS figures in a spreadsheet or document before you log into the portal. Have every number ready. Then log in, enter everything quickly in one session, and lodge.

The ATO provides downloadable BAS worksheets that you can use for preparation. Some accounting software also allows you to prepare BAS offline and upload when ready. The key is minimising the time you spend logged into the portal with an incomplete form.

When the Portal Still Won't Work: Your Lodgement Options

Technical fixes don't always work, and the deadline doesn't care. The ATO applies Failure to Lodge penalties at one penalty unit per 28-day period overdue, up to five units. Using these alternative lodgement methods is better than missing the deadline entirely.

Lodging through your registered tax agent portal access

Registered tax agents have separate portal access that often works when the business portal is down. If you're a tax agent, your agent portal login is different from your business client access.

Businesses can authorise their tax agent to lodge on their behalf if they're experiencing access issues. If you work with a bookkeeping service like Absolutebooksnbas, they can often lodge through their professional access while you're locked out of yours.

Phone lodgement with the ATO (and how to avoid the 90-minute wait)

Phone lodgement is an official option. Call the ATO business line on 13 28 66. You'll need your BAS figures ready and your ABN and TFN for verification.

Timing matters. Call early morning between 8am and 9am, or after 4pm to avoid peak wait times. The ATO will send written confirmation of phone lodgements within 48 hours.

Requesting penalty remission for access-related delays

Technical access issues are considered 'reasonable cause' for penalty remission requests. Penalties can be reduced or waived if you provide reasonable grounds to the ATO.

The process: lodge as soon as you can access the portal, then immediately request remission explaining the technical issue. Document everything. Take screenshots of error messages, note timestamps, save any error codes. This supports your remission request and shows you made genuine attempts to lodge on time.

Why This Keeps Happening (And What's Actually Changing)

The 2025 authentication migration created ongoing integration issues between myGov, myGovID, and ATO systems. Multiple login handoffs between different platforms create more points of failure.

The ATO is aware of these access problems and is working on system improvements through 2026. Future updates aim to simplify authentication and reduce the number of login handoffs. But right now, the systems are still stabilising.

Bookmark this guide. Keep alternative lodgement options ready. If you're consistently struggling with BAS access and lodgement, working with specialists like Absolutebooksnbas can remove the technical burden entirely. They handle the portal access, the lodgement process, and the compliance requirements while you focus on running your business.

The portal issues will improve. Until they do, you now know what actually works when you're locked out.