Would it be easiest enough to just use conditional formatting in K5 to identify anything less than 365 days?
Conditional Formatting- Highlight applicable range >> K5:K100
- Home Tab >> Styles >> Conditional Formatting
- New Rule >> Use a formula to determine which cells to format
- Edit the Rule Description: Format values where this formula is true: =$K6-$N$2<365
- Format… [Number, Font, Border, Fill]
- OK >> OK