> ## Documentation Index > Fetch the complete documentation index at: https://docs.runway.com/llms.txt > Use this file to discover all available pages before exploring further. # Prorated salaries > Use Runway’s date math functions to model prorated salaries for employees who start or leave mid-month with precision. This guide walks through adding a prorated salary field to your HRIS-sourced Employee database. As a reminder, HRIS databases work differently than other Runway databases. For more information, please refer to our [HRIS databases article](https://docs.runway.com/concepts/databases/hris-databases#hris-databases). ## Step 1: Create `Prorated Monthly Salary` field In your **Employee database**, add a **Number field**. Prorated Salaries Step1 Create Field Pn Name the field **Prorated Monthly Salary**. ## Step 2: Handle mid-month starts 1. Add a formula to **Prorated Salary**. Begin with an `if()` statement that checks if the start date falls within the current month. Prorated Salaries Step2 1 Pn 2. If true, use the `dateDiff()` function to calculate the difference in days between the start date and the end of that month. You'll also want to add 1 day onto this, to ensure you're including the starting day too. Prorated Salaries Step2 2 Pn 3. Use `daysInMonth()` to divide by the total days in the month and calculate the prorated percentage. Prorated Salaries Step2 3 Pn 4. Multiply this prorated fraction by the employee's monthly salary (annual salary divided by 12). Prorated Salaries Step2 4 Pn ## Step 3: Account for mid-month terminations Extend your `IF()` formula to account for employees who terminate mid-month by adding a second condition. 1. Add a second `IF()` statement by copying the formula so far, and pasting it at the end. 2. Then, update `This Employee.Start Date` to `This Employee.Termination Date` by clicking on each reference of `This Employee.Start Date` -> hitting *Column* -> and then referencing `This Employee.Termination Date` instead. 3. Next, you'll want to update the dateDiff() function so that the first argument is the *start* of the termination month, and the second argument is just the Termination Date itself. Prorated Salaries Step3 Pn ## Step 4: Calculate full-month salaries Finally, handle the default case where the employee worked the full month. Set the final case to the (annual) pay rate / 12 for full-month employees. Prorated Salaries Step4 Final Formula Pn Hit **Enter** to save your formula and review your data. This column formula automatically applies to all employees in your database. Prorated Salaries Step4 Save Pn For additional information about headcount planning, see [this article](https://docs.runway.com/guides/modeling/headcount-planning).