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This calculator computes the amount of interest due on disbursements of back pay issued under the authority of 5 U.S.C. 5596 and 5 CFR part 550, subpart H. The Internal Revenue Service quarterly interest rates for back pay are updated on January 1, April 1, July 1, and October 1 each year and are the source used to calculate the interest due. You can find the list of Interest Rates Used for Computation of Back Pay here. The OPM back pay interest calculator uses these interest rates (pre-loaded) back to April 1, 1989. (The calculator cannot be used to compute interest for periods prior to April 1, 1989. You may find Internal Revenue Service Interest Rates – Archive List from periods July 1, 1975, through December 1, 1989, here.) Even though the dollar amounts shown in the summary report produced by the back pay calculator are rounded to 2 decimal places, all calculations were actually performed to the 9th decimal place at all intermediate computation stages. Only the final results were rounded to 2 decimal places.

When using this calculator, follow your agency's policy on using and saving Personally Identifiable Information (PII).

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Disclaimer: This calculator is a tool provided to help compute an employee's back pay interest award. The material and tools displayed on this website are provided without any guarantees, conditions or warranties as to their accuracy. The reliability of the calculations produced depends on the accuracy of the information you provide. If there are concerns about accuracy please re-check results by referencing the back pay law and regulations at 5 U.S.C. 5596 and 5 CFR part 550, subpart H and by using manual computations methods.

What this calculator does

• Calculate back pay and interest awards, using automatically updated IRS quarterly interest rates.
• Save a back pay case to your local computer and upload and edit an existing case from your local computer.
• Print a summary report of the completed calculations from a case.

Information needed to use the back pay interest calculator

• Payroll calendar(s) for the back pay period from the employee's Shared Service Center or Payroll Provider.
• Actual gross pay received by the employee and corrected gross back pay for each pay period during the back pay period.
• Outside earnings statement (if applicable).

Additional Information

Additional information on the operation of this calculator may be obtained from the Office of Personnel Management's (OPM's) Pay and Leave office at pay-leave-policy@opm.gov. Information about specific back pay cases or individual employee payroll or human resources records must be obtained from the employee's agency human resources office or payroll provider. OPM does not maintain such information and is not responsible for computing back pay awards.

Identifying Information Section

Recipient's Name

Enter the name of the back pay recipient in the First, Last, and Middle name fields. These fields are optional.

NOTE: If multiple records are created for the same recipient, we suggest you save the file under different name identifiers.

Special Notes

Enter any special notes or other important information about this case. This field is optional.

Pay Periods and Interest Section

Field #1 - Number of days in employee's pay period

Enter the number of days in the employee's pay period during the back pay period. The default value is 14. If this employee has a pay period other than 14 days, click on the box and type in the appropriate number of days. You must start a new case if the numbers of days in an employee's pay period changes during the back pay period. This is a required field.

NOTE: If necessary, contact the employee's human resources office or payroll provider for information on the number of days in the employee's pay period.

Field #2 - Number of days between end of pay period and date that paychecks are issued

Enter the number of days between the end of the pay period and date that paychecks were issued for the employee during the back pay period. There is no default value. You must start a new case if the numbers of days in an employee's pay period changes during the back pay period. This is a required field.

NOTE: If necessary, contact the employee's human resources office or payroll provider for information on the number of days between the end of pay period and date that paychecks are issued.

Field #3 - First day of first pay period for which back pay is payable

Enter the first day of the first pay period for which back pay is payable (MM/DD/YYYY). This is a required field.

You can either type the date in the box or you can click on the calendar button. If you click on the calendar button, first select the year by clicking on the down arrow to the right of the year displayed. Use the slider to locate the appropriate year. Next select the appropriate month and then click on the date. The date will automatically appear in the box.

Field #4 - First day of last pay period for which back pay is payable

Enter the first day of the last pay period for which back pay is payable (MM/DD/YYYY). This is a required field.

You can either type the date in the box or you can click on the calendar button. If you click on the calendar button, first select the year by clicking on the down arrow to the right of the year displayed. Use the slider to locate the appropriate year. Next select the appropriate month and then click on the date. The date will automatically appear in the box.

Field #5 - Date on which back pay interest stops accruing

Enter the date on which back pay interest stops accruing (MM/DD/YYYY). This is a required field.

You can either type the date in the box or you can click on the calendar button. If you click on the calendar button, first select the year by clicking on the down arrow to the right of the year displayed. Use the slider to locate the appropriate year. Next select the appropriate month and then click on the date. The date will automatically appear in the box.

NOTE: The days/dates in fields #2, #3, #4, and #5 must align properly before you can calculate back pay and interest. An error message will appear if the days/dates are not properly aligned.

Outside Earnings Section

Click on Yes or No in response to the question "Did the employee have outside earnings during the period of time in which the employee was erroneously separated due to an unjustified or unwarranted personnel action?" Clicking "Yes" or "No" is required.

• If you click No, continue to the Pay Period Data section.
• If you click Yes, enter Total outside earnings during the period of erroneous separation. This is a required field.
• Click on the Continue button and proceed to the Pay Period Data section.

NOTE: By law, an employee's back pay award must be offset by the amount of any outside earnings. The outside earnings factor will be computed based on the amounts you entered and will be automatically applied to each pay period. The calculator automatically subtracts outside earnings (when outside earnings amounts are entered) and results can be seen in the summary report of the back pay and interest calculation. See 5 U.S.C. 5596 and 5 CFR part 550, subpart H, for additional information on outside earnings.

Pay Period Data Section

Gross Pay field

Enter Gross Pay actually paid to the employee during each pay period. This is a required field.

Corrected Gross Pay field

Enter Corrected Gross Pay that the employee should have received during each pay period. This is a required field.

NOTE: You can use the tab key to easily navigate this section. Also, you can use a combination of the tab key and ctrl C (copy)/ctrl V (paste) to complete only the Corrected Gross Pay column. You may not edit the Date Range or Pay Date columns in this section. The dates listed in this section are calculated based on the dates and number of days entered in the Pay Period and Interest section. Also, corrected gross pay must be higher than gross pay or you will receive an error message.

Form Controls

Calculate Back Pay

After you enter all the information and data into the required sections of the calculator as described above, click the Calculate Back Pay button. The calculator will:

• Calculate the gross back pay (offset for any outside earnings) and interest for the back pay period; and
• Display the Back Pay Computations Summary Report in a new pop-up screen, which will contain detailed information on this back pay case. (See Back Pay Computation Summary Report for additional information.)

Reset Form

By clicking the Reset Form button, you can clear the entire form and all the data entry screens will be cleared.

Back Pay Computation Summary Report

The Back Pay Computation Summary Report provides information on the back pay case including the detailed information entered into the calculator and the total gross back pay and interest award. The following are definitions of the columns in the Detailed Computation section:

Pay Per.

This is a sequential number of pay periods entered into the calculator. Note that the last "pay period" displayed in the table is actually the final period of interest accrual, not an actual pay period.

Date Range

The beginning date of each pay period calculated from the information entered in the Pay Period and Interest section and the ending of each pay period calculated from the information entered in the Pay Period and Interest section.

Pay Date

The pay date for each pay period calculated from the information entered in the Pay Period and Interest section.

Leap Year

Indicating yes or no, if the pay period falls in leap year (automatically determined by the calculator).

No. of Days

The number of days in employee's pay period from the information entered in the Pay Period and Interest section.

Gross Pay

The amount of pay the employee actually received during each pay period entered in the Gross Pay field in the Pay Period Data section.

Corrected Gross Pay

The amount of pay the employee should have received during each pay period entered in the Corrected Gross Pay field in the Pay Period Data section.

Gross Back Pay

The difference between the Gross Pay and Corrected Gross Pay during each pay period.

Adj. Back Pay

This is either the same amount in the Gross Back Pay column (if there are no outside earnings) or the amount calculated after applying the outside earnings factor calculated in the Outside Earnings section.

Tot. Adj. Back Pay

The cumulative total of the amounts for current and prior pay periods entered.

Interest Rate

The Internal Revenue Service quarterly interest rates for back pay are updated on January 1, April 1, July 1, and October 1 each year and are the source used to calculate the interest due. The interest rates displayed in the summary report are those that apply to the period of time covering your back pay case.

Daily Rate

The daily computed interest rate for this pay period.

Tot. Interest

The cumulative total of the interest calculated as of the pay date for this pay period.

Total

The cumulative total of adjusted back pay and interest due as of the pay date for this pay period.

Adjusted Gross Back Pay Plus Interest

The total gross back pay plus interest that may be due to the employee.

Summary Controls

Edit Information

By clicking the Edit Information button from the Back Pay Computation Summary Report screen, you can go back and edit any information in all data entry sections of the calculator.

Print

By clicking Print from the Back Pay Computation Summary Report screen, you can print the summary report for this case.

Save

By clicking the Save button from the Back Pay Computation Summary Report screen, you can save your case to your local computer or network for uploading at a later date. When you click this button, a new pop-up screen will open directing you to save the case to your local computer or network. You can save a case at any time during the data entry process to upload later. Cases will be saved as an .xml file. You can save other copies of the final results for viewing outside of the calculator by using your local computer’s “save as PDF” function, if available.