Sharing a Mac with another user: whose time gets recorded
· 6 min read
On a Mac with more than one user account, a time record belongs to the account it runs in and sees nothing outside it. Your login records your day, the other login records theirs, and neither can read the other. That is a consequence of how macOS separates accounts, not a setting anyone chose.
This answers most of the questions people have about a shared family Mac or a machine handed between two people. It also sets a hard limit on one thing readers sometimes want, which is covered plainly below.
Each account is its own world
A user account on macOS gets its own home folder, its own preferences, its own login items and its own running apps. When an app records which app is frontmost, it can only see the session it is running in. There is no view from one account into another, and an app that tried to get one would need permissions a well-behaved utility has no business asking for.
The storage follows the same boundary. A record lives inside your home folder, for example at ~/Library/Application Support/Punchcard/punchcard.sqlite, and the tilde is the important character: it resolves to your home folder and nobody else’s. Another account on the same Mac has its own path with its own file, and by default cannot read yours. Where Mac apps keep your data, and how to find it walks through the layout if you want to look.
So the answer to “whose time gets recorded” is: whoever is logged in, in their own session, with their own copy of the app running.
What fast user switching does to a day
Fast user switching (the account menu at the right of the menu bar, or System Settings, Users and Groups) lets a second person log in without the first person logging out. Both sessions stay loaded. Only one is on screen.
The useful thing to understand is that a frontmost app is a property of the session that owns the screen. When your session is switched away, your apps are still in memory but nothing in your session is in front of anybody. When you switch back, your session picks up where it left off.
What this means for a day’s numbers is best checked rather than assumed, because the shape depends on how long the switch lasted and what you left in front. The practical test takes one evening:
- Note the time, then switch to the other account.
- Leave it there for fifteen minutes and do something in that account.
- Switch back, and note the time again.
- Look at your record for that window: does the fifteen minutes appear against whatever you left in front, or is it absent?
Do it once and you know how your own setup behaves, which is worth more than a general claim. Reading your own time data with sqlite3 in the Terminal has the commands for reading a single day row by row, which is exactly the resolution this test needs.
If the time does land on your account, the fix is the same as for any away-from-the-desk stretch: lock the screen with Control-Command-Q before switching, and treat the gap as honest.
A shared family Mac, realistically
The common setup is one Mac, one work account, one account for everything else, or a household machine with an account per person. That arrangement suits a per-account record well.
- Your work account holds your work record. Nothing from the family account leaks into it, which is what makes the daily total meaningful.
- Recording in the other account is a separate decision. If you want a record there too, that account needs its own copy of the app running in its own session. Whether that is worth doing depends on whether anyone will read it.
- Ending the day cleanly matters more on a shared Mac. If the machine passes to someone else at six, logging out or locking at six is what draws the line in your record.
Two Macs raise a different question, which is whether the two days can be read together. How to track time across two Macs covers that, and the honest answer there also applies here: a record that never leaves the machine does not merge itself.
What you cannot do, and why that is right
You cannot use a personal time record to watch another account on the same Mac. Not a partner’s account, not a child’s account, not an employee’s. The data does not cross the boundary, and the app has no feature for it.
This is deliberate rather than an omission. Punchcard asks for zero macOS permissions: no Accessibility, no Screen Recording, no Full Disk Access. It records app names only, never window titles, document names, URLs, keystrokes or screen contents, and it contains no networking code at all, so there is nowhere for another account’s day to be sent even in principle. It has no team features, no accounts and no dashboard for anyone but you.
If the actual need is oversight of someone else’s computer use, that is a category of software with very different properties, and it should be chosen knowingly rather than improvised out of a personal tool. What employee monitoring software sees, and what a personal tracker should not draws the line where it belongs. For a child’s Mac, macOS Screen Time with Family Sharing is the supported route and the one designed for consent and visibility.
Checking what your own account holds
If you have inherited a Mac or you are not sure which account a record belongs to, three checks settle it:
- Log in as yourself and look in Finder. Go, then Go to Folder, and enter
~/Library/Application Support/. What is there belongs to the account you are in. - Check login items per account. System Settings, General, Login Items and Extensions is a per-account list. An app that starts for you may not start for anyone else.
- Export what you have. A CSV export is a file you can move, keep or delete on your own terms, and it makes the per-account boundary obvious the moment you try to combine two of them.
Deleting is equally per-account. “Burn the roll” removes everything recorded in the account you are logged into, and leaves any other account untouched, because it was never able to touch it in the first place.
Questions
If I create a second account for work, does my existing record move? No. A new account starts empty. The old record stays in the account that made it, and you would need to export CSV from one and keep it separately rather than expecting it to follow you.
Does the guest account keep a record? The guest account is erased when it logs out, so anything stored in it goes with it. Treat guest sessions as unrecorded.
Can an administrator account read another user’s file? An administrator can reach other users’ files on the same Mac with enough effort, which is true of every file in every home folder and not specific to a time record. Encrypting the disk with FileVault and not sharing administrator accounts is the real protection.
Does a shared Mac need two licenses? A license covering two Macs is about machines, not accounts. Use it on the Macs you own, and check the terms rather than guessing if the situation is unusual.