Who pays when an AI agent files or pays something wrong?

Who caused it and who owes it are different questions

When an AI agent files a return, makes a payment or submits a claim, it acts in the name of the business it works for. The agent may have done the work and the vendor may have built the workflow. Neither fact, on its own, means the outside party will pursue the vendor instead of the business.

Payroll taxes show how firm this is. The IRS says that when a business outsources payroll, “the employer is ultimately responsible for the deposit and payment of federal tax liabilities,” and that “in the event of default by a third party, the employer remains responsible for the deposit of the federal tax liabilities and timely filing of returns.”

The exact result depends on the kind of arrangement. In the IRS’s words, a business that uses a third party for these tasks “may remain solely liable for Federal employment taxes, may become jointly and severally liable for such taxes or may be relieved of liability for such taxes.” Relief is the exception. For example, a certified professional employer organization is treated as the employer for wages it remits, and “no other person shall be treated as the employer” for those wages.

A missed deposit adds a loss on top of the tax

The payroll tax itself was already owed. The mistake creates an extra cost when the deposit is late, short or sent the wrong way. IRS Publication 15 for 2026 sets the federal failure-to-deposit penalty, under 26 U.S.C. § 6656, as follows.

The IRS counts the days late in calendar days, starting from the due date. Interest runs on top.

Here is a worked example. An employer owes a $100,000 federal deposit and an automated workflow sends it seven days late. Seven days falls in the 5% tier, so if no relief applies the penalty is $5,000. The $100,000 was always owed. The $5,000 is the loss the failed job caused.

The case is worse if a provider took the employer’s money for the tax and never sent it. The IRS still holds the employer responsible, so the employer can end up paying the same tax twice.

Relief can change the final number. The penalty does not apply when the failure “was due to reasonable cause and not to willful neglect,” and the IRS may waive it in limited first-time cases, such as an inadvertent failure in the first quarter a business had to deposit, subject to size and net-worth limits.

State filings carry their own penalties. See sales tax penalties by state for one example.

Can the business recover the cost from the vendor?

Only as far as the vendor contract allows. A vendor contract may include a limitation of liability, which caps what the vendor owes and can exclude indirect losses entirely. Penalties and interest can be argued to be indirect, or “consequential,” losses, and a contract that excludes those may leave nothing to recover.

Courts do not always read these clauses the way vendors hope. Under the Uniform Commercial Code, a limited remedy that “fail[s] of its essential purpose” can be set aside. New York’s highest court has held that losses which are “the natural and probable consequence of the breach” can be direct damages even when a contract excludes consequential ones. But a business that has to sue its vendor to find out has already lost time and money.

A better test than asking whether the vendor is “responsible” is to ask what money the business could actually recover after one specific failed job.

Will insurance pay?

The business’s own policies may not respond to a mistake made by a vendor’s product, so check the wording. The vendor’s errors and omissions insurance, if it has any, protects the vendor against its own liability, which brings the question back to the contract. A certificate of insurance on its own does not tell the business what it will receive. Standard policy forms now also include optional exclusions for generative AI. See AI exclusions in liability insurance.

What a guarantee changes

A guarantee is a direct promise from the vendor to make a specific kind of mistake right, for example by paying the penalty from a late filing it caused. It does not depend on proving who was legally at fault, and it can be written to reach costs that a liability cap would exclude. The most useful guarantees are precise. They say which job is covered, what counts as a failure, which loss is paid and up to what amount, and what proof settles it. How a guarantee relates to a warranty and to insurance is explained in warranty vs guarantee vs insurance.

Questions to answer before an AI agent files or pays for you

1. If the agent files late or pays the wrong amount, who still owes the agency, bank or payer?
2. Which part of the bill was owed anyway, and which part exists only because the job failed?
3. What contract language says who repays that extra part, and what limit applies?
4. What proof would show the job failed, and how long do you have to report it?
5. For payroll, what kind of third-party arrangement is it? The IRS says that can decide whether the business stays solely liable, shares liability or is relieved.
6. How will you know the work landed? For federal tax deposits, the IRS suggests employers enroll in EFTPS themselves to confirm payments.

The terms used here are defined in the glossary.