Need formula to calculate sick day entitlement based on anniversary date

Hello,
I have basic excel skills and need assistance with a formula(s). We have employees, with over 90 days of employment, that get 5 sick days to start with as this is a new provision. I will need a formula to auto-populate 5 days when they reach their anniversary date and/or when they reach their 90 day employment period. Any days not used in their anniversary year do not roll over to the following year.