what is the meaning of this sentence?" The employee is required to submit a medical certificate if the self declared sick leave exceeds 1 day excluding weekly offs or declared public holidays,"
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The sentence means that if you are only away sick from work for one day, you can "self-declare" - you say you were sick and the company will believe you. However, if you are sick for more than one working day, you must get a certificate from your doctor to show that you were sick.
The last part means that days you don't normally work are not included, and nor are national holiday days.
Here are some examples:
I normally work Monday to Friday each week. This week, I was off sick on Thursday but I returned to work on Friday. I do not need a certificate as I was only sick for one working day.
I normally work Monday to Friday each week. This week, I was off sick on Wednesday and Thursday but I returned to work on Friday. I need to provide a medical certificate because I was off sick for 2 days.
I work Monday to Friday. Last week, I was off sick on Friday. I continued to be sick on Saturday and Sunday but I returned to work on Monday. I do not need a medical certificate as I was only sick for one working day (Friday). Saturday and Sunday do not count.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.