Savings with maturity lump-sum tax

Accrue monthly savings by compounding and apply tax to accumulated interest at maturity.

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Calculation basis and official references

Reviewed on:

Formula basis

Monthly interest accrues as balance×annual rate/12 and is capitalized monthly, semiannually, or annually. In maturity-tax mode, tax equals cumulative gross interest×tax rate and is deducted once; 20.315% is the default for ordinary taxable deposit interest.

Calculation method

Simulates initial principal and monthly contributions, capitalizes accrued interest at the chosen interval, and applies the entered tax rate once to cumulative interest at maturity.

Exclusions and checks required

  • Monthly accrual, compounding dates, maturity-only tax, and rounding order are calculator assumptions, not bank rules.
  • The NTA source supports only the 20.315% default, not compounding, tax timing, or rounding.
  • Product-specific taxation, tax-exempt accounts, fees, holidays, actual days, and changing rates are excluded.

Example input:：JPY 1 million initially plus JPY 50,000 monthly for 10 years

annualRate
1.2
rounding
floor
years
10
monthlyMan
5
initialPrincipalMan
100
compounding
monthly
taxMode
maturity
taxRate
20.315

Tax and maturity value apply the entered rate under this calculator's maturity-tax assumption.

Official references

FAQ

Who is this calculator for? Savings with maturity lump-sum tax

Accrue monthly savings by compounding and apply tax to accumulated interest at maturity.

What values should I enter?

Applies to: Savings / Interest is accrued and capitalized at each compounding date, then taxed in a single lump-sum at maturity.

How should I interpret this estimate?

Simulates initial principal and monthly contributions, capitalizes accrued interest at the chosen interval, and applies the entered tax rate once to cumulative interest at maturity.

How to use

  1. Enter your input values and press Calculate.
  2. Review the result and compare it with expected context.
  3. Monthly interest accrues as balance×annual rate/12 and is capitalized monthly, semiannually, or annually. In maturity-tax mode, tax equals cumulative gross interest×tax rate and is deducted once; 20.315% is the default for ordinary taxable deposit interest.

Official references