Bond Ladders: Tracking Maturity Dates and Reinvestment

General
1

I’ve built a 5-year Treasury bond ladder and finding Beancount tracking to be both powerful and tricky.

My Ladder Structure

  • Year 1: USD 10,000 in 1-year Treasury
  • Year 2: USD 10,000 in 2-year Treasury
  • Year 3: USD 10,000 in 3-year Treasury
  • Year 4: USD 10,000 in 4-year Treasury
  • Year 5: USD 10,000 in 5-year Treasury

Each year, the maturing bond gets reinvested at the 5-year rate.

Recording Bond Purchases

2026-01-15 * "Buy 5-year Treasury"
  Assets:Investments:Bonds:Treasury5Y  10,000 TREAS5Y {1.00 USD}
  Assets:Bank:Checking                  -10,000.00 USD
  maturity-date: 2031-01-15
  coupon-rate: 4.25%

The Maturity Challenge

When a bond matures, I need to:

  1. Record the principal return
  2. Record final interest payment
  3. Remove the bond position
  4. Buy the new 5-year bond

Questions

  1. How do you query for upcoming maturities?
  2. Anyone track accrued interest for bonds bought between coupon dates?
  3. Tips for managing the reinvestment workflow?
2

For querying upcoming maturities, I use a Python script that parses metadata:

from beancount import loader
from datetime import date, timedelta

entries, errors, options = loader.load_file('main.beancount')

upcoming = []
for entry in entries:
    if hasattr(entry, 'meta') and 'maturity-date' in entry.meta:
        mat_date = entry.meta['maturity-date']
        if mat_date <= date.today() + timedelta(days=90):
            upcoming.append((mat_date, entry))

for mat_date, entry in sorted(upcoming):
    print(f"{mat_date}: {entry.narration}")

Recording Maturity

Here’s my full maturity workflow:

; Bond matures
2027-01-15 * "Treasury 1Y matures"
  Assets:Investments:Bonds:Treasury1Y  -10,000 TREAS1Y {1.00 USD}
  Assets:Bank:Checking                  10,000.00 USD  ; Principal
  Income:Interest:Treasury               -200.00 USD   ; Final coupon

; Reinvest at the long end
2027-01-15 * "Buy 5-year Treasury (reinvestment)"
  Assets:Investments:Bonds:Treasury5Y  10,000 TREAS5Y {1.00 USD}
  Assets:Bank:Checking                  -10,000.00 USD
  maturity-date: 2032-01-15
  coupon-rate: 4.50%
  reinvested-from: "TREAS1Y-2026"

The reinvested-from metadata creates an audit trail.

3

On the accrued interest question—this trips up a lot of people.

The Problem

If you buy a bond between coupon dates, you pay the seller for interest they’ve earned but haven’t received yet. This is accrued interest.

Example: Bond pays semi-annual coupon Jan 15 and Jul 15. You buy Mar 15.

  • Seller earned 2 months of interest (Jan 15 - Mar 15)
  • You pay them that accrued interest
  • On Jul 15, you receive the full 6-month coupon

Recording Accrued Interest

2026-03-15 * "Buy Treasury mid-coupon"
  Assets:Investments:Bonds:Treasury  10,000 TREAS {1.00 USD}
  Assets:Bank:Checking               -10,100.00 USD
  Income:Interest:AccruedPaid            100.00 USD  ; Accrued interest paid to seller

2026-07-15 * "Receive semi-annual coupon"
  Assets:Bank:Checking                    200.00 USD  ; Full 6-month coupon
  Income:Interest:Treasury               -200.00 USD

Net Interest Income

Your actual interest income is the net:

  • Received: USD 200
  • Paid (accrued): USD 100
  • Net: USD 100 (4 months of ownership)

Query to see true interest income:

SELECT sum(number(position))
WHERE account ~ 'Income:Interest'
4

I want to add a perspective on why bond ladders rather than bond funds.

Bond Ladder vs Bond Fund

Bond fund (like BND):

  • No maturity date
  • NAV fluctuates with interest rates
  • You might sell at a loss

Individual bonds (ladder):

  • Known maturity date
  • Hold to maturity = get your principal back
  • Interest rate changes don’t affect you if you hold

When Ladders Make Sense

  1. Retirement income: Known cash flows on specific dates
  2. Liability matching: Save for a car in 3 years, buy a 3-year bond
  3. Interest rate uncertainty: Lock in rates without NAV risk

My Dashboard Query

I run this to see my ladder at a glance:

SELECT 
  currency,
  meta("maturity-date") AS maturity,
  meta("coupon-rate") AS rate,
  sum(cost(position)) AS principal
WHERE account ~ 'Assets:Investments:Bonds'
GROUP BY currency, maturity, rate
ORDER BY maturity

This shows me exactly when each rung matures and at what rate.