Treasury Securities Can Offer a Hidden State Tax Break for Savers in High-Tax States

A certificate of deposit and a Treasury bill may offer the same headline rate, yet a saver in New York can end up with very different after-tax results. The difference has less to do with the investments themselves than with state tax rules.

Consider a retiree in New York with cash to set aside for a year. Her bank offers a one-year CD, while TreasuryDirect offers a 52-week Treasury bill. Because the rates appear similar, she may simply stay with the bank she already knows.

That decision can reduce her net return. New York taxes the CD interest but leaves Treasury interest untouched, so the posted yield does not tell the full story.

Treasury Interest Is Excluded From State Income Taxes

IRS Publication 17 explains that interest from Treasury bills, notes, and bonds is taxable at the federal level but exempt from state and local income taxes. These securities are U.S. obligations, meaning they are issued directly by the federal government. The interest appears in box 3 of Form 1099-INT.

Interest from bank CDs, savings accounts, and corporate bonds usually does not receive that treatment. It is generally subject to federal tax and, in most states with income tax, is also included on the state return.

States provide their own subtraction rules for Treasury interest. New York Tax Law § 612(c)(1) allows residents to subtract interest income on obligations of the United States from federal income. The New York Tax Department explains on its Information for retired persons page that this adjustment lowers New York adjusted gross income and directs taxpayers to Form IT-225. California law similarly states how certain obligations are exempt from state taxation.

Why a Lower Treasury Yield Can Still Produce More After Tax

A tax-equivalent yield helps compare the two options fairly. This is the rate a taxable investment would need to pay to leave an investor with the same after-tax income as a tax-favored one.

Because both CDs and Treasuries are subject to federal tax, the main difference is the state tax layer. The higher a state’s top income-tax rate, the more a CD must yield to match a Treasury. New York City residents also avoid city income tax on Treasury interest, which increases the advantage further. Investors should compare after-tax returns using their own tax bracket, since the advertised rate can be misleading.

Bills, Notes, Bonds and TIPS Qualify, but Funds Need Extra Attention

Publication 17 lists the securities that qualify. Bills mature in 4, 8, 13, 26, or 52 weeks and are sold at a discount, so the interest is the difference between the purchase price and face value. Notes mature in more than 1 year and up to 10 years. Bonds mature in more than 10 years. TIPS (Treasury Inflation-Protected Securities) pay a fixed rate on a principal amount that rises and falls with inflation. All four qualify for the state tax exemption.

Treasury money market funds and Treasury bond funds may pass along the exemption for the portion of income tied to U.S. obligations. But states set their own rules. New York and California both require a fund to hold at least 50% of its assets in qualifying obligations at the close of each quarter. If a fund falls below that threshold, residents cannot exclude any of the income. The fund’s year-end tax statement shows the share derived from U.S. government securities.

Municipal bonds work differently. Interest on state and local bonds is usually exempt from federal tax, but the state benefit generally applies only to in-state bonds. New York adds back interest on obligations of other states.

Three Situations Where the Treasury Tax Break Can Fade

• No state income tax means no added benefit. In states such as Texas or Florida, Treasuries and CDs are taxed the same way, so the posted rate decides the winner.
• TIPS can create taxable income before cash is received. Under Publication 550, investors must report yearly increases in inflation-adjusted principal as original issue discount, even though the money is not paid until maturity.
• Selling before maturity introduces market risk. When rates rise, existing notes and bonds tend to fall in value. The 10-year yield moved from 4.61% to 5.31% over a later period, and anyone who sold an older note during that rise likely took a loss. Holding to maturity avoids that price risk and returns face value.

Account type matters as well. In a tax-deferred retirement account, the state exemption provides no benefit because withdrawals are taxed as ordinary distributions. Treasury interest is still federally taxable, so it can affect the income tests used for Social Security taxation and Medicare premiums.

Who Benefits Most From Treasury Securities

The largest gains go to retirees in high-tax states who keep significant cash balances or CD ladders in taxable brokerage accounts. New York City residents benefit twice because Treasury interest escapes both state and city income tax. Before the next CD matures, it is worth comparing after-tax yields rather than relying only on the headline rate.