How to create a bonus income in payroll so that the net value is a specific dollar amount (reverse calculation)?

10% on amounts up to and including $5,000;
20% on amounts over $5,000 up to and including $15,000; and
30% on amounts over $15,000.

Rates are different for the Province of Quebec.

Please consult CRA website for official information: Canada Revenue Agency: Withholding rates for lump-sum payments

CAUTION: 

Canada Revenue Agency requires that all income be taxable including bonuses.

Workaround: I want the net to be the actual bonus (for example $500.00)

1. The information below is to guide you to do a manual reverse calculation starting from the net $500 to figure out the gross (which is higher than $500).
2. Sage recommends you verify your calculation(s) with your accountant.
3. Turn off the auto calculation of payroll by pushing the button to manually calculate taxes.
   • 10th icon of 16 at the top of the paycheque window
4. Calculate the necessary taxes manually to add to the net to get the gross. You will need the CRA and/or provincial tax tables for your own references.
5. Below are examples for reverse calculation.
   • Note, if you have additional deductions or taxes, then please add those into your reverse calculation.

Example 1: for a 500$ bonus with applicable rates for July 2013

1.88% EI rate
4.95% CPP rate
10.0% Fed tax rate
16.83% total
100% - 16.83% = 83.17%
$500 / 83.17% = $601.18

So, with a gross of $601.18

$11.30 EI
$29.76 CPP
$60.12 tax (10%)
$101.18 total
$601.18 - $101.18 = $500.00

Example 2: for a $10,000 bonus with applicable rates for july 2013

$10000 / .7317 = $13,666.80
$256.94 EI
$676.51 CPP
$2733.36 tax (20%)
$3666.81 total
$13666.80 - $3666.81 = $9999.99

Note1: CPP needs to be a manual calculation at 4.95% as there should be no use of the 3500 exemption amount
Note2: If there is a penny difference. Make a simple adjustment on one of the lines
Note3: If CPP, EI, or both are maxed out (or max out during the bonus cheque), verify the procedure with an accountant.
Note4: All these rates are for july 2013 and affect all provinces except for Quebec.