Is the employee a 'He' or a 'She'? Not that this matters, but your responses give mixed indications. Anyway, 'she' may show that she doesn't care about salary, but actually, everyone does. A delayed promotion/increment (or demotion in this case) (as compared to other peers getting these perks) always affects a person. She may show that for one or two instances it did not affect her, but in the long run, she will surely feel it. Try to have a candid discussion with her and understand her concerns. Also, give clear indications of these long-term effects on her career with this background.
If you want to make it an example to highlight your office punctuality rules, then surely suspension is one of the suitable disciplinary actions. Though, the effectiveness of it 'for this employee' might not be as you expect. It does not take time to multiply such behavior amongst employees starting from one isolated case. But punishment does not necessarily stop it. You have to work towards modifying the office culture where coming late does not even come to the mind of employees.
As I said before, if this is just one employee creating a bad environment in an otherwise good office culture, then it will be better to let her go than trying to rectify her.
Follow-up Questions
1. Does she also stay back in the office and work until late?
2. Is her work effective, and does the late coming affect her productivity? Except for this one concern, how is her overall performance?
3. Even though she does not care for the salary, does she really care for her assignments and the company welfare?
4. Is she being given less work so she feels her presence in the office full time is not necessary? Have you tried increasing her workload? Maybe give some additional extracurricular responsibility like internal trainings?
5. What is her relative position in the organization? What is the strength of her department? Have you tried to collect 360-degree feedback for her?
6. What is her job profile—physical or mental efforts work?
7. What is the general attendance record and punctuality in the workplace otherwise?
8. Do you have a union/work associations in the workplace? What is the job security in your organization?
Answers to these questions would also affect the possibility/effectiveness of suspension as disciplinary action. This might not be the scenario, but sometimes such cases are indications that the company policies need to upgrade to the next level (like +/- 1-hour flexible office timing for everyone).
Best Regards,
Amod Bobade.