Fixed income financing is the arrangement in which a government or company borrows money directly from investors by issuing bonds, promising a fixed schedule of interest payments and the return of the original loan amount on a set date. The borrower gets capital up front. The investor gets a predictable income stream and a legal claim to be repaid. That predictability is what gives the asset class its name, and it is why bonds sit at the center of most retirement portfolios, pension funds, and government budgets.
The Three Terms That Define Every Bond
A bond is a contract. When it is written, three numbers are locked in, and everything else in fixed income flows from them.
The first is the principal, also called par value or face value. This is the amount the borrower promises to repay when the loan ends. For most bonds, par is $1,000 per bond.
The second is the coupon rate, the annual interest rate expressed as a percentage of par. A 5% coupon on a $1,000 bond pays the investor $50 a year, usually split into two $25 payments six months apart. That rate does not move. Whatever happens to interest rates in the wider market over the life of the bond, the coupon on this bond stays at 5%.
The third is the maturity date, the day the borrower must return the full par value. Maturity can be as short as 90 days or as long as 30 years. Once those three terms are set, both sides know every dollar that will change hands and when.
If the borrower misses any scheduled payment, coupon or principal, that is a default. Default can push a company into bankruptcy, damage its credit rating, and shut it out of future borrowing. For the investor, it can mean recovering only part of the investment, or nothing at all.
How Fixed Income Differs From Equity
A company that needs money has two ways to raise it: borrow it or sell a piece of itself. Fixed income is the borrowing side. Buying a bond makes you a creditor. You have a contractual right to your coupons and your principal, but you get no vote on how the business is run and no share of its profits beyond the coupon you agreed to.
Buying stock makes you an owner. Shareholders vote, receive dividends when the board declares them, and gain if the share price rises. Nothing is guaranteed. If no dividend is paid and the price falls, the shareholder has no contractual claim to fall back on.
The clearest place this split shows up is bankruptcy. Bondholders are paid before stockholders. Secured bondholders, whose bonds are tied to specific assets, come first. Unsecured bondholders follow. Equity holders sit at the back of the line and often receive nothing once the debts are settled. That priority is the trade-off at the heart of fixed income: less upside than stock, a stronger legal claim than stock.
The Main Types of Fixed Income Instruments
Who issues the debt shapes the risk, the yield, and the tax treatment. A handful of categories cover most of what an investor will encounter.
U.S. Treasury Securities
The U.S. Treasury borrows to fund federal operations, and its debt is considered among the safest in the world because it carries the full backing of the U.S. government. Treasury debt is sorted by maturity into Treasury Bills (one year or less, sold at a discount rather than paying coupons)1TreasuryDirect. Treasury Bills, Treasury Notes (2 to 10 years, semi-annual interest)2TreasuryDirect. About Treasury Marketable Securities, and Treasury Bonds (20 and 30 years, also semi-annual).3TreasuryDirect. Understanding Pricing and Interest Rates
Inflation-Protected Securities
Fixed coupons carry a hidden weakness. Inflation quietly eats away at the purchasing power of every payment. The Treasury offers two instruments built to counter that.
Treasury Inflation-Protected Securities (TIPS) come in 5, 10, and 30-year terms. Their principal adjusts up and down with the Consumer Price Index for Urban Consumers (CPI-U), and because the coupon is a percentage of that adjusted principal, the interest payments move with inflation too.4TreasuryDirect. Treasury Inflation-Protected Securities (TIPS)
Series I Savings Bonds combine a fixed rate that never changes with an inflation rate that resets every six months against CPI-U. For bonds issued from November 2025 through April 2026, the composite rate is 4.03%, built from a 0.90% fixed rate and a 1.56% semiannual inflation rate.5TreasuryDirect. I Bonds Interest Rates An individual can buy up to $10,000 in electronic I bonds per calendar year per Social Security number.6TreasuryDirect. I Bonds
Municipal Bonds
State and local governments issue municipal bonds to pay for infrastructure, schools, and public services. The draw for investors is the tax treatment: interest is generally excluded from federal income tax, and sometimes from state and local tax as well.7Municipal Securities Rulemaking Board. Municipal Bond Basics
Two subtypes matter. General obligation bonds are backed by the full taxing power of the issuing government. Revenue bonds are repaid only from the income of a specific project like a toll road, hospital, or water system. Revenue bonds tend to be riskier because repayment depends on one revenue stream rather than a government’s whole budget. Credit quality varies significantly from one issuer to the next, so ratings do real work in the municipal market.
Corporate Bonds
Companies issue bonds to fund factories, acquisitions, and general operations. The credit quality of the issuer sets both the risk and the coupon it must pay. Moody’s, S&P, and Fitch rate corporate debt on parallel scales.
Bonds rated BBB- (or Baa3 at Moody’s) and higher are investment grade, meaning default is considered relatively unlikely. Anything at BB+ (Ba1) or lower is speculative, commonly called high-yield or junk. The gap is not small: S&P’s own data show a three-year cumulative default rate of 0.91% for BBB issuers, compared with 12.41% for B and 45.67% for CCC/CC.8S&P Global Ratings. Understanding Credit Ratings Higher default risk is exactly why high-yield bonds must offer larger coupons to attract buyers.
Zero-Coupon Bonds and STRIPS
Not every bond pays coupons. Zero-coupon bonds sell at a deep discount to face value and pay no interest along the way. The investor’s entire return is the difference between what they paid and the par value they collect at maturity.
The Treasury enables this through STRIPS (Separate Trading of Registered Interest and Principal of Securities). A standard note or bond is broken apart so that the principal payment and each individual interest payment become their own zero-coupon securities, each with its own maturity. STRIPS trade through brokers and dealers, not directly through TreasuryDirect.9TreasuryDirect. STRIPS
Securitized Products
Securitization pools individual loans into a single tradable bond. Mortgage-Backed Securities (MBS) bundle home loans and pass through borrowers’ monthly payments. Asset-Backed Securities (ABS) do the same with auto loans, credit card receivables, and other consumer debt. Both carry prepayment risk that plain bonds do not: when homeowners refinance or borrowers pay off early, the investor gets principal back sooner than expected and has to reinvest it at whatever rate the market is offering, which is usually a lower one.
How Bonds Are Priced After Issuance
Every bond begins in the primary market, the initial sale from borrower to investor. The Treasury runs public auctions. Corporations typically hire investment banks to underwrite new issues, which means the bank buys the bonds and resells them to investors, absorbing the risk of finding buyers.
After that first sale, the bond trades in the secondary market between investors. Most bonds trade over-the-counter through dealer networks rather than on a centralized exchange. A dealer buys a bond from one investor, holds it, and later sells it to another at a markup. That structure makes bond pricing less transparent than stock pricing. There is no single ticker showing a continuously updated price.
The Price-Yield Relationship
The most important dynamic in bond trading is the inverse relationship between price and interest rates. When new bonds arrive offering higher rates, existing bonds with lower coupons become less attractive, and their market prices drop until the effective yield lines up with what new bonds are paying. When rates fall, the reverse happens and existing higher-coupon bonds trade above par.
This is where the difference between coupon rate and yield matters. The coupon is locked at issuance. A 5% coupon on a $1,000 bond always pays $50 a year no matter what the bond’s market price does. Yield-to-Maturity (YTM) is the total annualized return an investor earns by buying at the current market price and holding until maturity. Pay $950 for that same bond and your YTM exceeds 5%, because you collect the $50 coupon each year plus a $50 gain when the full par value is repaid at the end.
The Risks Behind the “Safe” Label
Bonds are often called safe, and against stocks they are. Risk-free is a different claim, and it does not hold. The main risks in fixed income work in ways that do not always match the intuition of an equity investor.
Interest Rate Risk and Duration
Rising interest rates push bond prices down. The longer the remaining maturity, the bigger the swing. A 30-year Treasury loses far more market value from a one-point rate increase than a two-year note does.
Duration is the standard measure of that sensitivity. It is the approximate percentage change in a bond’s price for a 1% change in interest rates. A bond with a duration of 7 would fall about 7% in price if rates rose one percentage point. Higher duration, more volatility.10FINRA. Bonds, Interest Rate Changes, and Duration For an investor holding to maturity, mid-life price swings are less important because par is still paid at the end. For anyone who might need to sell early, duration is a direct measure of the market risk being carried.
Credit Risk
Credit risk is the chance the borrower cannot make its payments. Treasuries carry almost none. Investment-grade corporates carry moderate credit risk. High-yield bonds carry a lot, which is the whole reason their coupons are higher.
Ratings are not fixed. When an agency downgrades an issuer, that issuer’s bond prices drop right away because investors demand more yield to hold weaker debt. Upgrades work the same way in reverse, though usually more slowly.
Call Risk and Reinvestment Risk
Many corporate and municipal bonds include a call provision that lets the issuer buy the bonds back before maturity at a set price. Issuers typically use this option when rates have fallen far enough that they can refinance more cheaply.11FINRA. Callable Bonds – Be Aware That Your Issuer May Come Calling
For the investor, that early return of principal comes at the worst possible moment, because reinvesting at the new, lower prevailing rates means locking in less income. That is reinvestment risk, and it hits callable bonds hardest because a call happens precisely when reinvestment options have gotten worse. Some callable bonds include a call protection period, often 10 years from issuance, during which the issuer cannot exercise the call.11FINRA. Callable Bonds – Be Aware That Your Issuer May Come Calling
How Bond Income Is Taxed
The tax treatment of interest depends entirely on who issued the bond, and misreading it can wipe out the after-tax edge you thought you had.
Interest from U.S. Treasury securities is taxed at the federal level but exempt from all state and local income taxes.12Internal Revenue Service. Topic No. 403, Interest Received In high-tax states, that exemption can make Treasuries more competitive than their stated yield suggests.
Municipal bond interest is generally exempt from federal income tax.7Municipal Securities Rulemaking Board. Municipal Bond Basics If the bond was issued by your own state, the interest is often exempt from state income tax as well. Out-of-state municipal bonds are usually taxable at the state level. The double exemption for in-state bonds is why advisors often steer high-bracket investors toward local issues.
Corporate bond interest is fully taxable at your ordinary federal rate plus any state and local tax. Nothing is sheltered, which is one reason corporate coupons have to be higher than Treasury or muni coupons to compete on an after-tax basis.
Zero-coupon bonds and STRIPS have a wrinkle that catches people out. Even though no cash arrives until maturity, the IRS treats the annual increase in the bond’s value as taxable income for that year. You receive a Form 1099-OID each year reporting the amount to include in gross income.9TreasuryDirect. STRIPS Holding zeros in an IRA or another tax-deferred account avoids the mismatch between owing tax and actually having the cash.
Why Borrowers Use Bonds Instead of Stock
From the issuer’s side, debt has several advantages over equity. The biggest is the tax deduction. Interest paid on business debt is generally deductible, which lowers the effective borrowing cost. A company in a 21% federal bracket paying 6% interest is actually borrowing at about 4.7% after the deduction. Federal law caps the business interest deduction at 30% of adjusted taxable income in most cases, so highly leveraged firms may not be able to deduct all of their interest.13Office of the Law Revision Counsel. 26 USC 163 – Interest
Debt also leaves existing shareholders untouched. Issuing new stock dilutes every current owner’s stake and vote. A bond issuance does not. Bondholders have no voice in how the company is run.
Governments have no equity option at all. They cannot sell shares of themselves, so debt is the only way to finance spending that outpaces tax revenue. Treasury and municipal bonds are how governments bridge that gap.
Where Fixed Income Fits in a Portfolio
Fixed income does a different job than stocks. Its purpose is capital preservation and steady income, not growth. That is why bonds anchor most diversified portfolios rather than drive their returns.
In stock sell-offs and recessions, high-quality government bonds often hold their value or rise as investors move money toward safety. That negative correlation with equities is what lets the bond side of a portfolio cushion the fall when the riskier side drops. Pension funds and insurance companies hold large fixed income positions for exactly this reason: they need reasonable certainty that they can meet future obligations.
Individual investors typically raise their bond allocation as retirement approaches, shifting from a growth-focused mix toward one built around predictable income and principal protection. A 60-year-old five years from retirement has far less capacity to wait out a stock downturn than a 30-year-old with decades ahead.
Individual Bonds vs. Bond Funds
Most retail investors get their fixed income exposure through mutual funds or ETFs rather than by buying individual bonds. Funds provide instant diversification across dozens or hundreds of issuers, pay monthly income, and accept small minimum investments. Building comparable diversification with individual bonds requires meaningful capital; holding fewer than about 10 different issues concentrates risk in a way that can undercut the stability bonds are supposed to add.
The trade-off is certainty of maturity. Owning an individual bond means you know exactly when your principal comes back, assuming no default or early call. A bond fund has no maturity date because the manager is constantly buying and selling, so the fund’s net asset value moves with interest rates and never settles to a fixed par. In a rising-rate environment, a bond fund investor can watch the account balance decline with no specific date on which it will recover. Investors who plan to hold to maturity and want that endpoint gain something real from individual bonds. Investors who value convenience and diversification lean toward funds.