There are three terms used around keeping your PPL valid. These are:
Competency Check and
In a nutshell, here is the difference:
The SKILLS TEST is what you do when you are testing for your initial PPL. You also do a SKILLS TEST if you have allowed your PPL to lapse for 5 years or more. The SKILLS TEST includes all the basic maneuvers of a COMPETENCY CHECK, but adds a few extra elements, such as the spiral dive recovery, cross wind take-off, power off recovery from a stall, extra in-flight emergencies and a couple of circuits, to demonstrate various landing configurations and approaches, and a long navigation, minimum 150nm with a few other stipulations.
The COMPETENCY CHECK is the "test" you fly with an Instructor within 90 days from the 12 month anniversary of your SKILLS TEST (based on the expiry date in your license, not the test date), and then again in 24 months and again in 24 months till you no longer pass your medical or decide to stop flying. This COMPETENCY CHECK can be done within 90 days of your license expiry date without losing and time on your license. The COMPETENCY CHECK done 91 days in advance, will, however bring your license renewal date forward.
You will notice your license will "expire" every year. This is because the SACAA are reminding you to pay your license fee to them. They want this annually. For them to earn this money, they want to do a summary of your logbook of the previous year, and to send them an Annual Submission Form, and yes, you can do this up to 90 days in advance too. They want you to email this to firstname.lastname@example.org.
RECENCY is you having done a minimum of three circuits and landings within the previous 90 days. This means you may take passengers.
For your renewals you are expected to have flown 3 hours PIC within the previous 6 months, and be RECENT.