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CD Ladder Income Forecast Estimator

Forecast the interest income a CD ladder may generate when some interest is reinvested and the rest is taken as cash. This estimator is designed for savers who want a multi-year view of ladder income instead of looking only at the quoted APY on a single certificate.

The model spreads an average annual yield across the number of maturity cycles you enter, then separates each period’s interest into a reinvested portion and a cash-income portion. It reports cumulative interest, cash received, and the projected balance at the end of the forecast. Actual renewals can occur at different rates, so the estimate is most useful for comparing scenarios such as lower yields, higher reinvestment, or a different maturity cadence.

Calculator inputs

USD
%
/yr
years
%
Result
—
Projected total interest earned
Cash interest received—
Interest reinvested—
Projected ending balance—
First-year simple interest—

1. Enter starting principal
Use the combined current balance of the CDs in the ladder.

2. Estimate a blended APY
Enter an average annual yield that represents the ladder as a whole.

3. Set the maturity cadence
Specify how many interest-and-renewal cycles you want the model to apply per year.

4. Choose the reinvestment share
Enter the percentage of each period’s interest that stays in the ladder instead of being taken as cash.

5. Set the forecast length
Review cumulative interest, cash income, reinvested interest, and projected ending principal over the selected years.

Periodic rate = APY / maturity cycles per year Period interest = current balance × periodic rate Reinvested interest = period interest × reinvestment percentage Cash income = period interest − reinvested interest Next balance = current balance + reinvested interest

The same average APY and reinvestment percentage are used throughout the forecast. Principal is not withdrawn in this model.

What the result means

Total interest earned combines interest taken as cash and interest reinvested into the ladder.

The projected ending balance includes only starting principal plus reinvested interest; cash interest is shown separately.

Given

  • Starting ladder balance: $80,000
  • Average APY: 4.0%
  • 4 maturity cycles per year
  • 50% of interest reinvested
  • 3-year forecast

Calculation
Periodic rate = 4.0% ÷ 4 = 1.0%
First-period interest = $80,000 × 1.0% = $800
$400 is reinvested and $400 is counted as cash income, then the process repeats for 12 periods.

Result
Total interest is approximately $9,868, split between cash income and reinvested interest.

Reinvesting part of the interest modestly increases later-period interest because the modeled balance grows.

Why is the forecast different from balance × APY × years?

The estimator allows reinvested interest to increase the balance used in later periods. A simple-interest calculation would not capture that compounding effect.

What reinvestment percentage should I use?

Use 0% if you expect to spend all interest and 100% if you expect to leave all interest in the ladder. Values between those extremes model a split strategy.

Does the number of ladder rungs have to equal the maturity cycles per year?

Not necessarily. Enter the number of income or renewal cycles you want to model during a typical year, which may differ from the total number of CDs you own.

Are CD rate changes modeled automatically?

No. The calculation uses one average APY for the full forecast, so it does not predict future market rates or bank renewal offers.

Is the cash-income figure after tax?

No. It is gross interest income before taxes. Use a tax-impact estimate if you want to translate gross CD interest into an after-tax amount.