Cashing-in is the mechanism for generating a certificate. If you have to complete three units in order to complete the AS qualification, and you do all three you won’t automatically get a certificate. Instead, the units will stay in your account. If you want a certificate to be generated, the cash-in must be applied for.

Cash-ins are automatically applied to eligible units toward the completion of a particular qualification. Depending on the subject, the units toward a certificate may differ.

Example 1. Science subjects such as Chemistry has 6 units
3 units (Units 1,2,3) for AS cashin toward an AS certificate
3 units (Units 4,5,6) for A2 cashin toward an A2 certificate

If you cash in for Units 1,2,3 you will be awarded an AS certificate for CHEMISTRY.
If you cash in for Units 4,5,6 you will be awarded an A2 certificate for CHEMISTRY.

Example 2. Humanities subjects such as History have 4 units
2 units (Unit 1,2) for AS cashin toward an AS certificate
2 units (Unit 3,4) for A2 cashin toward an A2 certificate

If you cash in for Units 1,2 you will be awarded an AS certificate for HISTORY.
If you cash in for Units 3,4 you will be awarded an A2 certificate for HISTORY.

Note that you cannot be cashed in for A2 certificate (the full A-level qualification) until you have completed all units toward that qualification.

Usually, cash ins are applied automatically as these can be reapplied in succeeding sessions should the student need to resit a unit toward a particular cashin, resulting in a new certificate to be issued with updated results.

Cash ins will not be applied for candidates who opt to cash in at the end, once the results for all units are final or if they are using units toward a particular qualification (as in the case of shared units toward Regular Math / Further Pure Math / Pure Math).

Late cashins can be applied for but are charged and take time to be applied.
This is particularly important if a student needs a final grade for qualifying to university as the university deadline might be approaching and if they did not cashin earlier, they will have to wait and it might be two or three weeks which is past their deadline. It is always better to cash in if eligible.