Gross-Up Tax Calculator

The article provides guidance on using Business.org's gross-up tax calculator recommended by BambooHR for payroll purposes. It explains the purpose of the calculator, which helps estimate an employee's net pay after taxes are withheld, particularly for one-time payments like bonuses. The article outlines how to access and utilize the calculator, including entering essential information such as state, net pay, gross pay year-to-date, pay frequency, exemptions, and federal and state filing statuses. Upon calculating, users will receive the gross-up amount needed to achieve the desired net pay. Additionally, it mentions an available downloadable tool for calculating various payroll scenarios, including gross-up pay and overtime. The article emphasizes the trial and error process often involved in achieving the correct gross wage.

  • Oct 21, 2025
  • Knowledge

Title
Gross-Up Tax Calculator
Article Text
Gross-up tax calculator is part of Payroll that is an add-on feature.

What gross-up tax calculator does BambooHR recommend for Payroll, and how do I use it?

Purpose: This guide will explain why we recommend Business.org's gross-up tax calculator. It will also walk you through how to use the tool to estimate a salaried employee's net pay with gross-up taxes.

Table of Contents:

Gross-up tax calculator

Tax calculators come in handy when figuring out how much to gross up an employee's taxes to make sure the employee receives the full amount of net pay promised, even after taxes are withheld. A tax gross-up is usually for one-time payments, such as a bonus check or relocation payment, but you can also gross up your regular payroll. 

We recommend using Business.org's Gross Up Calculator to help you calculate and find these estimates. Business.org uses Symmetry, the same trusted tax engine BambooHR® Payroll uses to ensure the most accurate payroll for your company. 

How to use the gross-up tax calculator

Before starting, ensure you have your employee's most recent paycheck handy. You can find this in BambooHR on the employee's Pay Info tab. Then, click on this link to access the calculator tool. We will outline how to use the calculator below. In the example, we will show how to gross up an employee's $2,000.00 one-time bonus. 

  1. State: Within the calculator tool, enter the state where the employee will be taxed. State information is underneath the Taxes section on the paystub.
  2. Net Pay: This is where you will enter the desired net pay amount for the employee. For this example, we used $2,000.00.
  3. Gross Pay YTD: Enter the amount of gross pay the employee has received so far this year. You can find this amount within the Total Taxable Earnings for 2025 section on the paystub.
  4. Pay Frequency: This will match the frequency of what is being grossed up. For example, a one-time/yearly bonus will be noted as "annual." In this example, Charlotte is receiving a bonus/reimbursement on a bi-weekly frequency.
  5. Exemptions: If the employee has any tax exemptions (federal, FICA, Medicare), you can indicate Yes for the exemptions that apply in this section. You can find this information below the Taxes section on the employee's paystub.
  6. Federal Information: Enter the employee's federal filing status and any other unique federal tax setups, such as allowances. In this example, we entered "Single" since this employee's state filing status is single.
  7. State Information: Now, enter the employee's state filing status and any other unique tax setups for the employee. You can find this information in the State section of the employee's paycheck. Again, in this example, we set the employee's state filing status to Single.
  8. Deductions: If an employee has a 401k, HSA, or any other type of deduction, you can add them in this section. In our example, this employee had three additional deductions that we set up as custom deductions. We entered the name and the dollar amount listed on the paystub. It is important to also change the amount type to $ Fixed Amount.
  9. Calculate: Once you have entered all of the employee's information, click Calculate.  

Gross-up calculations

Once you click Calculate, a box will appear at the top of the calculator with the gross-up amount needed for the employee to receive the desired net pay. You can then enter this amount within Gross Wages section on the Edit page for that employee when running payroll. In this example, I will need to adjust Charlotte's gross wage to $2,765.03 for her to receive a net income of $2,000.00.

Please note that this process often requires a few rounds of trial and error, inputting different gross wage amounts, until you calculate the desired net income. This is because the tax amount changes as the taxable wages increase or decrease. 

Additional calculator tools

Our Payroll Services team has created a calculator tool that you can download and use to help calculate gross-up pay, RSU post-tax deductions, prorated pay, overtime pay, and Safe Harbor matches. Follow the instructions within each tab and only adjust the highlighted cells. 

Payroll Calculation Examples.xlsx
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