Every payslip involves some amount of “shrinkage” between the gross salary written in your contract and the net amount that reaches your bank account. That shrinkage generally falls into two categories: income tax, and mandatory statutory deductions. They’re related but distinct, and understanding the difference makes it much easier to read a payslip or a salary calculator’s results without confusion.
Income tax
Income tax is collected by the national tax authority and funds general government spending. Most countries covered on this site use a progressive Pay As You Earn (PAYE) system, where income is divided into bands and each band is taxed at an increasing rate. Employers are typically responsible for calculating and withholding this tax automatically on every payday, remitting it to the tax authority on your behalf — which is why it’s called “Pay As You Earn.”
Mandatory statutory deductions
Separately from income tax, most countries require specific contributions to be deducted from employee salaries for defined purposes — most commonly a pension or retirement savings scheme, and often health insurance or a similar social program. Unlike general income tax, these contributions are usually earmarked: pension contributions build toward your own future retirement benefit, for example, rather than funding general government spending.
Common examples include pension or social security contributions, unemployment insurance, health insurance, and country-specific levies. The names change from country to country, but the practical effect is similar: they reduce the cash salary you receive, and they should be shown separately so you can see where the money is going.
These deductions typically come with their own rules, separate from the income tax bands — a fixed percentage rate, sometimes with a minimum earnings threshold below which it doesn’t apply, and often a cap on the earnings the percentage is calculated against (so very high earners don’t keep paying more and more into the scheme indefinitely).
Before-tax vs after-tax deductions
One detail that trips up a lot of manual calculations: in some countries, certain mandatory deductions are subtracted from gross salary before income tax is calculated, which lowers your taxable income as well as your take-home pay. In other countries, income tax and mandatory deductions are calculated independently, both based on the same gross salary. Getting this order wrong can meaningfully change the result, especially at higher deduction rates — which is why a generic, one-size-fits-all salary formula will consistently under- or over-estimate take-home pay.
Caps, floors, and thresholds
Many deductions are not simply “salary multiplied by a percentage.” Some have a minimum contribution, some only begin once pay crosses a threshold, and some stop increasing after earnings pass a cap. A capped pension or social security contribution can feel large at low and middle salaries but become a smaller share of pay for high earners. That is one reason the effective deduction rate can change as salary rises.
Reading a deductions breakdown
A good salary calculator itemizes every deduction separately rather than lumping everything into a single “tax” figure — showing income tax, and then each mandatory contribution by name, with its own amount. This site’s country-specific calculators do exactly that: enter a gross salary for Uganda, Kenya, South Africa, the UK, or Nigeria, and see income tax and every mandatory deduction listed individually, alongside your resulting net pay and effective tax rate.
What salary calculators usually leave out
Public calculators normally focus on statutory employee deductions because those rules can be checked against official sources. They often leave out personal items such as voluntary pension top-ups, staff loans, salary advances, private insurance, union dues, medical credits, employer-specific benefits, or reliefs that require personal details. That does not make the calculator useless; it means the result is a clean baseline, and your payslip may add personal adjustments on top.