HMRC Basic Paye Tools not working on iMac: 'Starting application' hangs

That's odd. 127.0.0.1 is localhost - a loopback port used for testing. If the PAYE app is trying to use localhost then it will fail. What's odd about this is that there was a post recently where a user who'd upgraded to 27 was having mail problems because Mail was trying to use 127.0.0.1 and, obviously, failing.

Hi all, concerning the latest update of MacOS Tahoe on my MacBook Pro, I have just tried the HMRC workaround using 'Terminal' and it works perfectly. You can open Basic PAYE Tools in Safari and carry on as normal.

Incidentally Basic Tools is still working on my iMac OS Tahoe on which I haven't done the last two security updates so it appears to be something in one of those it didn't like. I'll delay updating the iMac and do the PAYE on that machine until the problem is resolved!

In the meantime use the HMRC workaround and good luck!

brettbaker wrote:

Having the same problems. My computer is on Golden Gate 27.0 and the software won't work. Thought I would install it on my wife's Mac which is running Sequoia 15.8 but the same thing happens.

Since it was working before and now isn't working on OS 27 nor 15.8 that would seem to indicate that the problem is on the government server side, not the user side.

I thought there may be a problem with the .gov website as well. Any theory is something in Golden Gate 27 and the update to Sequoia 15.8 which happened at the same time as Golden Gate was released is blocking the software from connecting to .gov.

In the startup log it its showing this message multiple times before refusing to start up:-

2026-09-28 11:12:40.491 - Info: [migrations] 1253 Frozen by py2app, now finding commands in /Applications/Basic PAYE Tools.app/Contents/Helpers/rti.app/Contents/Resources/lib/python2.7/bptrti/management

Does this mean anything to anyone please?

Hi, I have transferred to Parallels too, very unimpressed with HMRCs attitude to Macs. Are you able to tell me what data file I need to transfer across or share with Windows/Parallel, as my new version is currently unpopulated.

Many thanks

I upgraded my Apple Mac OS to Sequoia 15.8.1 and cannot open my HMRC rti app. The HMRC fix using Terminal instructions does not work. Has anyone found a solution to this. My rti.app is stored under Applications / HMRC / payetools-rti / rti.app. Thanks for any suggestions.

Iain well done, the software is amazing, thank you for providing it. The HMRC suggestion worked but was a bit clunky.

The PAYE Tools software now loads faster than ever before. I think HMRC need to be talking to you to get their software fixed.

No problem. I made it for myself but figured I was not the only one dissatisfied with the workaround as posted so decided to make it available and tell people.

I do worry they’ll stop supporting Mac but if that happens I’ll see if I can’t make it work. There’s some great analysis about the software by Angus Forrest https://angusforrest.com/posts/reverse-engineering-hmrc-basic-paye-tools which is super helpful at looking at the insides.

I decided to make something that would survive updates easily. But if the end comes then I’ll try and keep something working instead of moving to parallels.

Thanks for the tool Iain. But on my Mac OS Sequoia 15.8.1, when I launch PayrollRTI.app it tells me that Basic Tools isn't installed. It is definitely installed on my Mac, and I've just reinstalled it afresh to make sure. PayrollRTI.app says that the expected location is "/Applications/Basic PAYE Tools.app". Is there a way to change the location as my Basic Tools is located here: Applications/HMRC/payetools-rti/rti.app. HMRC's Terminal solution is also not working for me, because when I paste each of HMRC's suggested commands into the Terminal it responds with "No such file or directory". Any ideas how I can get Basic Tools to work? Cheers!

Having the same problems. My computer is on Golden Gate 27.0 and the software won't work. Thought I would install it on my wife's Mac which is running Sequoia 15.8 but the same thing happens.

Hi, I have the same problem, re-installed app, added rosetta, just in case.

Maybe a problem with .gov website?