The CD ladder blueprint: how to build one and what it costs

Which of these are you?

• You have a lump sum you will not touch for a year or more and want some of it back on a schedule: build the ladder in this chapter. Start at the worked example below.
• You have no emergency fund yet: stop here. The first 24 months of a ladder are Tier 3 money, and the first two tiers come first. Read the three-tier framework.
• You already own one long CD and wonder whether to break it into a ladder: do not break it for the shape alone. Run the penalty math in the early withdrawal chapter, then start the ladder with new money as the CD matures.
• You want the ladder to pay a known bill on a known date: size the rungs backward from each bill. That is Chapter 7, and this chapter gives you the equal-rung version to start from.

What problem does a CD ladder solve?

A ladder solves two problems that a single CD leaves open: all of your money reprices on one date, and all of it is penalty-locked until that date. Spreading maturities gives you cash on a schedule and lets you change your mind on a schedule.

Take $50,000 in one 5-year CD. For five years none of it can move without an early withdrawal penalty, and on the day it matures every dollar meets whatever the market is then paying. If rates are lower that day, all $50,000 reinvests low. If rates were higher a year earlier, you missed that too. Concentrating the maturity concentrates both risks in one afternoon.

A ladder splits the exposure. With five rungs, only $10,000 reaches a maturity date in any one year, so only 20 percent of the money is ever repriced at once. You are never forced to guess the right year to lock the whole balance. You also get a rung of cash every year that you can spend, move to a higher rate, or roll forward, without paying a penalty to get to it.

The ladder does not create yield. It rearranges when you get your principal back, and you pay for that flexibility with a lower blended rate when longer terms pay more than shorter ones. Later sections put a dollar figure on that price.

How is a ladder built, and how do you measure it?

A ladder is N equal rungs whose terms step up by a fixed spacing s, so maturities fall s months apart. Its two measurable properties are the spacing, which is your time between cash events, and the average remaining maturity (the mean months to maturity of a fresh ladder), which is s x (N + 1) / 2 months for a freshly built ladder.

The variables: N is the number of rungs, s is the months between maturities, rung k has term k x s months, and each rung holds capital divided by N. The average remaining maturity of a new ladder is the mean of the terms: s x (1 + 2 + ... + N) / N, which simplifies to s x (N + 1) / 2. The table applies it to four shapes. Every figure is in months.

Average remaining maturity grows with both the number of rungs and the spacing, so a longer, wider ladder gives up more liquidity for whatever extra yield the longer terms pay. And the share of money maturing per event is simply 1 / N, so adding rungs makes each maturity smaller and each decision lower stakes.

One correction to a common description. A "6-month, 1-year, 18-month, 2-year, 3-year" ladder is often called a six-month ladder, but its last gap is 12 months, not 6. Its maturities are uneven, so the formula above does not apply to it. If you want an evenly spaced six-month ladder, the fifth rung is 30 months.

Terms are set by what banks actually sell, and each bank offers a fixed menu of them. A monthly or odd-spaced ladder is therefore often built by opening the same term on different dates rather than by hunting for unusual terms. Chapter 7 covers that method.

Worked example: five annual rungs on $50,000

Split $50,000 into five $10,000 CDs with terms of 1, 2, 3, 4 and 5 years. Using hypothetical APYs rising from 4.00% to 4.40%, the ladder blends to 4.20%, returns $10,000 of principal per year, and earns $6,786.93 in interest by the day the last rung matures.

The rates below are round hypotheticals chosen to show the mechanics. They are not current quotes and not a forecast. The formula for each rung is maturity value = principal x (1 + APY)^(term in months / 12), with annual compounding at the stated APY and taxes excluded. Interest is maturity value minus principal.

Check rung 3 by hand: 10,000 x 1.042^3 = 10,000 x 1.13137 = $11,313.66. The blended APY is the simple mean of the five APYs because the rungs are equal in size: (4.00 + 4.10 + 4.20 + 4.30 + 4.40) / 5 = 4.20%. Average remaining maturity is 12 x (5 + 1) / 2 = 36 months, and the first cash arrives at month 12.

Try your own figures. The calculator defaults match the table, and every number it prints comes from the same tested functions as the article. Replace the APYs with the rates you are quoted before you open anything.

For today's market, the best CD APY we track across all terms is 4.50% APY, and the CD ladder optimizer adds after-tax income and liquidity warnings on top of the schedule. Compare term by term on the 1-year and 2-year pages before you fix the rungs.

What do you do when the first rung matures?

Roll the matured rung, principal plus interest, into a new CD at the longest term on the ladder. In the example that is a new 5-year CD. Repeat each year and after five years every rung is a 5-year CD, still maturing one year apart.

Rung 1 matures at $10,400.00. That amount goes into a new 5-year CD. The ladder now holds terms of 1, 2, 3 and 4 years remaining on the original rungs, plus 5 years on the new one, so the remaining maturities are 12, 24, 36, 48 and 60 months again. Average remaining maturity is back to 36 months, and it stays there each year you repeat the step. The formula holds for a ladder in steady state as well as a new one.

This is the mechanism behind the "rung a year" promise. After the first year you hold long-term rates, which often pay the most, and you still get a maturity every 12 months. In this hypothetical, the cost of the setup year was that four of the five rungs were shorter than five years and earned the lower short-term rates.

You are not obliged to roll into the longest term. A matured rung is new money, and the choice that matters is the one you make about that money, not about the ladder. If you need the cash, take it. If the longest term pays less than a shorter one, Chapter 8 covers that case. What the roll rule gives you is a default that keeps the structure intact when you have no better plan.

How fast does the ladder reprice when rates move?

A ladder reprices one rung per maturity, so a permanent 1 percentage point change in reinvestment rates moves the blended APY by 0.2 points after the first rollover, 0.4 after the second, and the full 1.0 point after five. On $50,000 that is $100, $200 and up to $500 a year of interest.

A ladder does not protect you from a rate move; it spreads the move across five years. The arithmetic: each rollover replaces 20 percent of the money at the new rate, so after k rollovers the blended APY has moved by k / 5 of the shift, and the annual interest on $50,000 has moved by $50,000 x 1% x k / 5.

The table applies equally to a rate fall, with the sign reversed. That symmetry is the reason to build a ladder when you do not want to be right about direction. If you do have a view, a single CD or a different structure expresses it more sharply, and Chapter 12 compares them with a calculator.

What does a ladder cost compared with one long CD?

In a normal rate environment where longer terms pay more, the ladder's blended APY sits below the longest CD's APY, and that gap is the price of scheduled access. In the hypothetical example it is $100 of first-year interest on $50,000.

The comparison: one 5-year CD at 4.40% earns $50,000 x 4.40% = $2,200 in year one. The ladder earns each rung's own APY on $10,000: $400 + $410 + $420 + $430 + $440 = $2,100. The difference is $100, or 0.20 percentage points on the blended rate. In exchange the ladder returns $10,000 at month 12 with no penalty.

That gap shrinks or vanishes when the curve is flat, and reverses when it is inverted, so the price of a ladder is a fact about the rates on the day you build it, not a constant. Rank the two structures on today's rates before you assume the ladder costs anything. The trade also depends on how likely you are to need the cash: a penalty on a long CD is a cost only if you break it, while the ladder's lower blended rate is a cost you pay for certain. If the chance of needing the money early is small, the certain cost can be the worse deal.

How much of the ladder belongs at one bank?

Each rung counts toward the same FDIC limit if the CDs are at one bank in one ownership category. FDIC insurance is $250,000 per depositor, per insured bank, per ownership category, and the amount of a deposit includes accrued interest (12 CFR 330.3(i)).

For a $50,000 ladder this is not a constraint. It becomes one when rolled interest pushes a bank total toward $250,000, or when the ladder is a large lump sum. Then the design question becomes how to spread rungs across banks, and Chapter 4 covers ownership categories and reciprocal networks. If you are choosing between one bank and several, our one-bank-or-many guide walks through the tracking tradeoff.

One bank means one login and one place to see every maturity notice. Several banks means you can buy each term where it pays the most, at the cost of more accounts and more dates. Nothing about the ladder mechanics changes either way.

What if you do not have all the money at once?

Build the ladder over time. Deposit each new rung as the money arrives and hold the waiting cash in Tier 2 savings until then. You give up the CD-versus-savings yield difference on the waiting balance, which is small for short waits.

There are two ways to do it. In the first, open the shortest rung first and add longer ones as cash comes in, so early rungs mature while later ones are still being funded. In the second, buy the same term repeatedly on a fixed calendar, which is the staggered-start method Chapter 7 uses for monthly and quarterly cadences. Both end at the same steady state described above, in which every rung is the longest term and maturities are evenly spaced.

Build checklist

The build takes five decisions. Write each one down before opening an account.

1. Amount. The total dollars you will not need before the first maturity. Rungs due within 24 months are Tier 3 money; rungs longer than 24 months are longer-horizon money outside the cash tiers, only for cash you will not need before they mature. Keep the emergency fund outside it.
2. Rungs and spacing. N and s. The average remaining maturity is s x (N + 1) / 2 months, and the first cash arrives at month s.
3. Split. Divide the amount by N. Unequal rungs are fine when a known bill sets a rung's size, as long as you write down why.
4. Open on one day. Opening every rung the same day keeps maturities evenly spaced. If your bank's minimum deposit is larger than a rung, the design fails, so check the minimum for each term before you fix the split. Minimums vary by bank and product.
5. Record every date. For each CD, write down the maturity date, whether it renews automatically, and how long the grace period is. Federal rules require the account agreement to state whether the CD renews and the grace period length, and require a notice before maturity for auto-renewing CDs longer than one month (12 CFR 1030.4(b) and 1030.5(b)). The notice is your reminder, but the calendar entry is your safeguard.