Apple ID change after giving iPad to family member

Logging-out from your Wife's iCloud account and other Apple services - and logging-in with your AppleID - is certainly an option, but there are two significant caveats of which you should be made aware.

1) When logging-out of iCloud, you are given the opportunity to leave a copy of iCloud data on the device. If you choose this option - and subsequently log-in to iCloud from this device with your AppleID - this saved-data will be “merged” with yours.

2) The Activation Lock associated with this iPad will remain tied to the AppleID last used to activate it (i.e., your Wife’s AppleID).

I hope this clarification is helpful.

First, copy/move any files/videos/data that you need to keep to Cloud storage (iCloud, Google Drive, Microsoft OneDrive etc) - then, ideally, follow this procedure to properly prepare the iPad to be used again by somebody else:

https://support.apple.com/en-gb/HT201351

At the end of this process, when setting-up again, you’ll have opportunity to create a new AppleID - which you should do unless you have already have a separate AppleID for your wife. If a separate AppleID already exists, use this instead when setting-up afresh.

I guess that you’ll want to share existing App purchases between you. There are a couple of ways to do this, but the Apple-recommended method is to set-up Family Sharing:

https://support.apple.com/en-gb/HT201088

My personal advice - whist it will be possible to both buy and share App purchases using either device and associated AppleID - would be to recommend that you discipline yourselves to making App purchases only from devices associated with the “lead” AppleID account; once purchased, Apps can be downloaded by others in the Family Sharing group.

Family Sharing Purchases are always charged to the lead account, but are ultimately “associated” with the AppleID that makes the App Store purchase. The reason for this strategy may become apparent if Family Sharing ceases to be your favoured method of sharing your Apps. Without getting into the alternative sharing-strategies, I hope this makes some sense.

Be aware that a device backup to your iCloud account (that will include items relating to your specific AppleID account) can only be restored to a device from your account - effectively returning the device-state to you.

Given your aims in context of purchased Apps and related services, you could simply log-out from iCloud and other services on the iPad that you intend your wife to use - and in so doing “locally” stored content will remain on the iPad.

As for ramifications, be aware that how you respond to system prompts, upon logging-out from iCloud, will determine whether Calendar, Notes, Keychain and other iCloud synchronised items are retained locally (or are purged) upon log-out from iCloud. If these items are retained, they will be merged with your Wife’s AppleID and iCloud content upon logging-in to iCloud. This action can result in unintended data “leakage” (e.g., passwords stored within the Keychain) between otherwise unrelated accounts - and/or duplicated items in shared resources.

I hope this information has been helpful in resolving your queries.