FinSmart calculation guide
Using the savings-tax example responsibly.
FinSmart calculates one year of simple interest and subtracts an illustrative percentage entered by the user. This is a transparent arithmetic example, not an official tax calculation.
The formula
interest before tax = principal × annual rate
illustrative tax = interest before tax × entered tax rate
ending balance = principal + interest before tax − illustrative tax
Why there is no universal default
Tax treatment depends on residence, account type, product, exemptions, filing status and current law. A rate that is common in one jurisdiction may be wrong in another.
What to enter
Use a rate from the relevant institution or official current guidance. Enter zero only when you have a valid reason to model no withholding or no tax.
What the example excludes
The calculator does not model compounding within the year, account fees, tiered rates, tax credits, deductions, reporting obligations or currency conversion.
Open the savings example · Read the methodology