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Bond Ladder Income Forecast Estimator

The Bond Ladder Income Forecast Estimator projects the interest income a bond ladder may generate over a selected horizon using a starting principal, average yield, and annual reinvestment rate. It separates first-year interest from cumulative interest so you can see how much of the forecast depends on reinvestment.

The estimate is useful for income planning, comparing ladder sizes, or stress-testing a lower yield assumption before purchasing bonds. It is deliberately portfolio-level: real ladders contain securities with different coupons, yields, maturity values, call features, and credit risk, so actual cash receipts will not be perfectly smooth.

Inputs

USD
%
years
%
Result
—
Forecast cumulative interest
First-year interest—
Ending modeled principal—
Average annual interest—

1. Enter ladder principal
Use the amount invested across the bond ladder at the start of the forecast.

2. Add the average yield
Enter a portfolio-level annual yield for the ladder.

3. Choose the horizon
Select how many years of interest income to project.

4. Set reinvestment
Enter the percentage of each year’s interest that is reinvested into the modeled principal.

5. Review income and principal
The forecast shows cumulative interest generated and the ending principal after the reinvested portion is added.

Interest_t = Principal_t × y
Principal_(t+1) = Principal_t + Interest_t × r

Here y is annual yield and r is the fraction of interest reinvested. Cumulative interest is the sum of annual interest over the forecast horizon.

The model assumes the same yield each year and does not reduce principal for maturities, defaults, withdrawals, premiums, or discounts.

What the result means

The main result is total modeled interest generated during the forecast period before taxes, whether that interest is spent or reinvested.

A changing rate environment or a ladder with uneven coupons and maturities can produce a materially different income path.

Given: $250,000 starting principal, 4.75% yield, 8-year horizon, and 50% of interest reinvested.

Calculation: Year 1 interest = $250,000 × 4.75% = $11,875. Half, or $5,937.50, is added to modeled principal for year 2. The process repeats for 8 years.

Result: Cumulative interest is approximately $103,283, with ending modeled principal of about $301,642.

Interpretation: Reinvesting half the interest modestly raises future interest because the modeled principal grows over time.

Is the forecast the same as yield to maturity?

No. Yield to maturity is a security-level return concept that depends on price, coupon payments, maturity value, and reinvestment assumptions. This estimator uses one average annual yield for the ladder.

What does 0% reinvestment do?

It keeps modeled principal constant and treats all interest as taken as cash. Cumulative interest then equals starting principal × yield × years.

Can the yield change by year?

Not in this simplified version. For a rate scenario, run the calculator several times with lower and higher average yields.

Does cumulative interest include returned principal?

No. The main result counts interest generated, while ending modeled principal is shown separately.

Are taxes deducted from the forecast?

No. Results are pre-tax. Tax treatment depends on the security and investor, so use a tax-impact estimator for an after-tax view.