Surety bonds explained: how they differ from insurance

A surety bond is a written guarantee by a surety company that you, the principal, will meet an obligation to a third party, the obligee. If you fail, the surety pays or arranges performance, and then you repay the surety. That last step is the difference from insurance: a surety bond transfers no risk away from you. It lends your obligee the surety's credit and leaves the loss with you.

Three parties, one promise

Every bond has the same cast.

• Principal. The business that owes the performance: a contractor, a licensed trade, an executor, a freight broker. The principal buys the bond and pays the premium.
• Obligee. The party the bond protects: a public owner, a state licensing board, a court, a customer. The obligee usually dictates the bond form and the amount.
• Surety. The company that stands behind the principal, with its own underwriting limit and a rating the obligee may require.

The bond states a penal sum, the most the surety will pay on the bond (plus, in many forms, costs). For contract bonds the penal sum is generally the contract price. For a license bond it is a fixed figure the statute sets. The conditions say that the bond is void if the principal does what it promised and stays in force if it does not.

Surety versus insurance

Surety is regulated by state insurance departments, written by insurance companies and reported by the NAIC as its own line. NAIC counted $11.40 billion of U.S. surety direct premiums written in 2025 (see the largest surety companies). But the economics run the other way.

A contractor's CGL policy (general liability insurance: what it covers and what it does not) pays a third party injured on the job. A performance bond pays the project owner if the contractor walks off. One does not substitute for the other, and a lender or public owner will usually want both.

The indemnity agreement

Before a surety issues a bond it usually requires the principal, and for a closely held company its owners and often their spouses, to sign a general indemnity agreement (GIA). In the standard form the indemnitors agree to reimburse the surety for every payment, legal fee and investigation cost, to post collateral on demand, and to let the surety settle claims in its discretion. The signers are typically jointly and severally liable, so the owners' personal assets can be reached. This is why surety underwriters treat a small contractor's balance sheet as a personal matter. Read the GIA before you sign it, and have an attorney read it if the bonding program is large, because spousal signature and collateral clauses can sometimes be negotiated.

The main families of bond

Contract bonds guarantee construction work. They are the bulk of the market: the bid bond, performance bond and payment bond, plus maintenance and subdivision bonds. bid, performance and payment bonds: how contract surety works covers them in detail.

Commercial bonds guarantee compliance with a law, a license or a duty. They include license and permit bonds, court bonds (fiduciary, appeal and similar), public official bonds, and customs and other regulatory bonds. license and permit bonds: who needs one and how they work explains the ones small businesses meet first.

Fidelity bonds protect an employer or a client from dishonest employees. They behave like crime insurance rather than true surety; see employee theft coverage and fidelity bonds: what they cover and who needs one.

Where bonds are required

Federal construction is the clearest case. The Miller Act, 40 U.S.C. 3131, requires a performance bond to protect the government and a payment bond to protect people who supply labor and material on federal construction. The statute's text says $100,000, but Federal Acquisition Regulation 28.102-1 applies the requirement to construction contracts over $150,000, and for contracts from $35,000 to $150,000 the contracting officer selects alternative payment protections (FAR 28.102-1, as revised effective March 13, 2026). Congress exempted the Miller Act from inflation indexing in the National Defense Authorization Act for fiscal year 2022, as the Surety & Fidelity Association of America noted, so the threshold stays at $150,000.

Each state has its own "Little Miller Act" for public works, with thresholds that vary widely. In the National Association of Surety Bond Producers' survey as of January 1, 2024, Arkansas shows $20,000 and California $25,000 for payment bonds, Texas $25,000 for payment bonds and $100,000 for performance bonds, and Minnesota $175,000. Thresholds change, so confirm the current statute for the state where you bid. Rules also differ for private projects, where owners and lenders ask for bonds by contract, and for licensing, where a bond may be a condition of the license.

Federal surety must come from a company on Treasury's Circular 570 list, which Treasury updated on August 1, 2026. Under 31 CFR 223.10 a listed surety may not write a single risk larger than 10% of its paid-up capital and surplus as determined by Treasury, except as the protective methods in 223.11 allow. That cap is one reason very large projects are often shared among co-sureties or reinsured.

How a claim works

When an obligee says the principal is in default, the surety investigates before it pays. A performance bond claim typically goes like this:

1. The obligee gives written notice of default and terminates or declares the principal in default, following the bond's notice conditions.
2. The surety investigates the contract, the principal's performance and the obligee's own conduct.
3. The surety chooses a remedy: finance the principal to finish, take over and complete with a replacement contractor, tender a completion contractor to the owner, or pay the obligee up to the penal sum.
4. The surety recovers its costs from the principal and indemnitors under the GIA.

Hypothetical example. A paving contractor holds a $2.4 million municipal contract and a performance bond for the same amount. It defaults when 40% of the work is complete, leaving $1,440,000 of contract balance unpaid. A replacement contractor bids $1.7 million to finish. The surety funds the $260,000 difference, plus its investigation and legal costs. It then demands repayment from the contractor and from the owners who signed the GIA. An insurer in the same position would simply absorb the loss.

What this means for a business owner

Treat bonding capacity as a credit line. The surety looks at your CPA-prepared financial statements, work-in-progress schedule, bank relationships, and the character of the owners. Show your bonding agent your numbers early, and bring in a specialist surety producer rather than a generalist who has never placed a bond (bonding capacity). The cost side, including why premiums are quoted as a percentage of the bond amount, is in what a surety bond costs and how it is priced, and the surety bond cost calculator gives an estimate once you know your bond amount and credit profile. If the obligee is a federal agency or a prime contractor on a federal job, expect additional insurance and bonding clauses; see insurance requirements for government contractors.

Key takeaways

• A surety bond is a three-party guarantee. The principal, not the surety, ultimately bears any loss, through the indemnity agreement.
• Premium buys the surety's credit and prequalification, so underwriting turns on character, capacity and capital instead of loss pooling.
• Contract bonds, commercial bonds and fidelity bonds are the three families; each has its own obligee and its own rules.
• The federal Miller Act threshold is $150,000 in FAR 28.102-1; state thresholds vary and change, so check the statute where you bid.
• Read the general indemnity agreement before signing: it can put owners' and spouses' personal assets behind the bond.