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FinToolSuite
Updated April 20, 2026 · Income · Educational use only ·

Second Job Income Calculator

Net hourly earnings from a second job after tax drag.

Calculate effective hourly pay from a second job after marginal tax impact. Enter hours per week and hourly rate to see net hourly pay and annual net income.

What this tool does

This calculator shows your net hourly earnings and annual take-home income from a second job, accounting for the marginal tax rate applied to additional earnings. When you earn above a certain income threshold, each extra pound is taxed at your marginal rate rather than a lower rate. The tool models how this affects your actual hourly pay and yearly contribution after tax. It takes your planned hours per week, hourly rate, and applicable marginal tax rate, then calculates both your net hourly pay and total annual net income from the second job. The result is an estimate for planning purposes and assumes a consistent working pattern throughout the year. It does not model social security contributions, pension deductions, or other withholdings that may also apply to additional income.


Enter Values

People also use

Formula Used
Gross hourly rate (entered as a percentage value)
Effective marginal tax rate (entered as a percentage value)

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Calculations or display — let us know.

Disclaimer

Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.

10 hours/week × 15/hour × 40% marginal rate = 9 net/hour = 4,680/year net. Second jobs often lose 30-50% to tax/NI as income stacks at marginal rate. Factor in before accepting — some side work better as self-employed for allowances.

A worked example

Try the defaults: hours per week of 10, hourly rate of 15, marginal tax rate of 40%. The tool returns 9.00 per hour. You can adjust any input and the result updates as you type — no submit button, no reload. That's the real power here: seeing how sensitive the output is to one or two assumptions.

What moves the number most

The result responds to Hours per Week, Hourly Rate, and Marginal Tax Rate. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.

The formula behind this

Marginal tax deduction on additional income. Everything the calculator does is shown in the formula box below, so you can check the math against your own spreadsheet if you want.

Using this in pay negotiations

Knowing the exact figure behind a headline rate gives you specific numbers to anchor to in conversations about pay. "The difference is £X per month after tax" lands harder than "a couple of grand a year". Concrete numbers move decisions.

What this doesn't capture

Tax bands, pension contributions, student-loan deductions, and benefits-in-kind sit outside this calculation. The figure is the headline; your actual position depends on local tax rules and personal circumstances. Pair with a dedicated take-home calculator for the full picture.

What to calculate alongside this

One figure by itself is fragile. The side hustle time vs income calculator, the amazon flex pay calculator, and the fiverr earnings calculator cover adjacent ground — the answer to any one of them changes how you read the output from this tool.

Example Scenario

Earning £15 per hour for 10 hours weekly yields 9.00 per hour in net income after 40 tax.

Inputs

Hours per Week:10
Hourly Rate:£15
Marginal Tax Rate:40
Expected Result9.00 per hour

This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.

Sources & Methodology

Methodology

This calculator computes net hourly earnings from a second job by applying a marginal tax rate to the gross hourly rate. The computation multiplies the hourly rate by the complement of the marginal tax rate (expressed as a decimal), yielding the after-tax hourly amount. The model assumes a constant marginal tax rate across all hours worked and treats tax as the only deduction from gross pay. It does not account for national insurance contributions, employment allowances, pension contributions, student loan repayments, or other statutory or voluntary deductions that may apply to your earnings. The calculation also assumes a linear tax relationship and does not model progressive tax brackets or variations in effective rates based on total annual income.

Frequently Asked Questions

Higher-rate trap?
Second job can push income into higher band. At 50,271+ → 40% tax. Second 10k of second job at 40% = 4k tax + NI.
Self-employed better?
1,000 trading allowance covers casual income. Above: expenses deductible, often 10-20% tax saving vs payroll withholding.
Opportunity cost?
10 hours/week second job = 520 hours/year. Could invest in skill development returning higher long-term.
Burnout risk?
Extra 500+ hours/year unsustainable long-term. Short bursts (6-12 months) fine for goal-based saving.

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