> ## Documentation Index
> Fetch the complete documentation index at: https://docs.symmetry.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Run a gross-up calculation

> Determine the gross pay needed to hit a target net pay with the gross-up calculator.

The gross-up calculator works backward from a target **net** pay to the **gross** wages required so that, after taxes and withholdings, the employee nets the target amount.

## When to use it

Reach for the gross-up calculator whenever the net is fixed and the gross is flexible:

* Net bonuses (for example, an employee should take home exactly \$5,000)
* Relocation payments
* Incentive or spot awards promised as a net amount

## Request

POST to the `grossup` endpoint with the target net pay in `netPay`:

```bash theme={null}
curl -X POST https://calculators.symmetry.com/api/calculators/grossup \
  -H "pcc-api-key: yourKey" \
  -H "Content-Type: application/json" \
  -d '{"state":"AZ","netPay":1500,"payFrequency":"WEEKLY","grossPayYTD":0,"federalFilingStatusType":"SINGLE","federalAllowances":0,"additionalFederalWithholding":0}'
```

The response `content` returns the solved `grossPay` plus the resulting taxes and `netPay`.

## Example

With `federalSupplementalFlat` set and a 2.5% Arizona withholding election, a \$1,500 target net for a Single filer paid weekly in Arizona solves to a gross of **\$2,210.77**. For the full breakdown and a hand check, see [How the gross-up calculation works](/cbs/core-concepts/gross-up-calc#worked-example).

## Behaviors to know

* **Additional federal withholding is added on top** of the grossed-up amount, not solved into it, so `grossPay − additionalFederalWithholding` reconstructs the base gross-up.
* **Supplemental settings change the result.** Setting `federalSupplementalFlat` (or a state supplemental flag) switches the method to flat; under flat supplemental, federal allowances don't affect the result. California has specific handling when a `SUPPLEMENTAL` state parameter is `BONUS` or `COMMISSION`.
* **Results can differ by a cent** from a hand calculation, because intermediate sums are rounded to two decimals only at the end. See [Known API behaviors](/cbs/api/known-behaviors).

For the concept behind this, see [How the gross-up calculation works](/cbs/core-concepts/gross-up-calc), and for the withholding method, see [Calculation methods by calculator](/cbs/core-concepts/calc-methods).