It is not just what is stated in your contract with the company but you also need to note what the current company policy is, regarding bonus payment and resignation date.

For eg., I have worked 30 years in this particular company and whatever contract terms there were regarding bonus payment and resignation have all but changed at the discretion of the company. Some for the better, others worse.

It used to be that as long as the bonus was paid to us, we could resign. Now, the terms were changed such that we cannot resign within the bonus month or the bonus paid will be recovered from us.