A common question homebuyers have is whether it is necessary to re-key the locks after they have purchased the home. You really have no way of knowing who has a copy of your keys. Prudence would dictate that it only makes good sense because you don't know how many keys have been made and who has them.

Re-keying the locks involves having the locksmith change the pins in the tumblers to require a new key to open the lock. This will render the previous key useless. Many homeowners find it convenient to have all of your locks, including deadbolts, keyed alike so that only one key is required. Of course, this will require that all of the locks be the same.

Another alternative is to replace all of the locksets with new ones. You can purchase name brand locks with new door handles at national hardware stores like Home Depot and Lowes. This will not only serve the purpose of re-keying but it will also give you new door handles that work well.

If the current door handles are standard size, it is a relatively easy job to replace the locksets.
If they're not, there will be some carpentry required. You can get a handyman for this project or buy the locks and have a locksmith do it for you. In any case, make sure that you maintain
control of the extra keys.

From a tax standpoint, re-keying a lock is considered maintenance that is not treatable on a personal residence but it is an expense on a rental property. However, most tax authorities would agree that replacing the locksets would qualify for a capital improvement that would give the homeowner some tax treatment.