My question is, can my employer anyhow access the data on my iCloud when I have it on the "company owned MacBook" without my permission?

Unless you give them access to your local credentials, your Apple ID credentials, or they have MDM (Mobile Device Management) software, they cannot access your files.

That said…

Don’t co-mingle your personal Apple ID with a company owned device.

The device is property of the company of course but we were told that for sign-in use our own personal Apple ID.

This is never a good idea. Here is just one example of what could go wrong: Resigned from a job, they are now asking me for my personal Apple ID and password to remove Activation Lock - does this make sense?

There’s a myriad of circumstances where you find yourself at their mercy because they will claim ownership of a device you’ve attached to your personal account. If this relationship goes sideways or they get legal summons, you might find yourself and your data on the wrong side of this relationship.

Mu advice is to not do this. They need to get Apple Business or something similar. This is exactly what it was designed for. If you must use an Apple ID, create a completely new one that you can treat as “disposable.”

My question is, can my employer anyhow access the data on my iCloud when I have it on the "company owned MacBook" without my permission?

Unless you give them access to your local credentials, your Apple ID credentials, or they have MDM (Mobile Device Management) software, they cannot access your files.

That said…

Don’t co-mingle your personal Apple ID with a company owned device.

The device is property of the company of course but we were told that for sign-in use our own personal Apple ID.

This is never a good idea. Here is just one example of what could go wrong: Resigned from a job, they are now asking me for my personal Apple ID and password to remove Activation Lock - does this make sense?

There’s a myriad of circumstances where you find yourself at their mercy because they will claim ownership of a device you’ve attached to your personal account. If this relationship goes sideways or they get legal summons, you might find yourself and your data on the wrong side of this relationship.

My advice is to not do this. They need to get Apple Business or something similar. This is exactly what it was designed for. If you must use an Apple ID, create a completely new one that you can treat as “disposable.”

My question is, can my employer anyhow access the data on my iCloud when I have it on the "company owned MacBook" without my permission?

Unless you give them access to your local credentials, your Apple ID credentials, or they have MDM (Mobile Device Management) software, they cannot access your files.

That said, don’t co-mingle your personal Apple ID with a company owned device,

My question is, can my employer anyhow access the data on my iCloud when I have it on the "company owned MacBook" without my permission?

Unless you give them access to your local credentials, your Apple ID credentials, or they have MDM (Mobile Device Management) software, they cannot access your files.

That said…

Don’t co-mingle your personal Apple ID with a company owned device.

The device is property of the company of course but we were told that for sign-in use our own personal Apple ID.

This is never a good idea. Here is just one example of what could go wrong: Resigned from a job, they are now asking me for my personal Apple ID and password to remove Activation Lock - does this make sense?

There’s a myriad of circumstances where you find yourself at their mercy because they will claim ownership of a device you’ve attached to your personal account. If this relationship goes sideways or they get legal summons, you might find yourself and your data on the wrong side of this relationship.

Mu advice is to not do this. They need to get Apple Business or something similar. This is exactly what it was designed for. If you must use an Apple ID, create a completely new one that you can treat as “disposable.”