While there is no strict, universal law governing how soon an invoice must be sent, it is best practice to send it immediately or within 30 days of completing work. Legally, invoices can generally be issued up to six years after services are rendered, based on statute of limitations for contract disputes in the US.
Although the legal time limits for invoicing are usually forgiving, you should send invoices within 30 days to maintain a steady cash flow. Electronic signatures can help you keep track of your invoices. Requesting digital signatures is fast, so you can do it before forgetting about the invoice.
There's no legal time limit that says you must invoice within a certain number of days (though doing it promptly is definitely best practice). So before you go spiraling into worst-case scenarios, remember: you're still entitled to be paid for the work you've done.
Under the Limitation Act 1980, invoices can be issued up to six years after the work was completed or the goods were delivered. While there is no legal restriction within this time frame, issuing invoices promptly is always best to avoid disputes or complications.
The general rule is 30 days from the invoice date. However, you can discuss this with your customer and either make it shorter or longer than 30 days. Regardless of what you agree upon, the payment terms and the due date should be clearly stated on the invoice.
According to California Code of Civil Procedure § 337(1), the statute of limitations for a written contract is four years. Under § 339(1), the limit for an oral contract is two years.
30+ days late
If your client hasn't made payment (or meaningful contact) within 30 days of the invoice becoming due, it may be time to issue a letter before action (LBA), or to pass over the matter to a debt collection agency. An LBA gives your client formal notice that legal action is imminent.
On the other hand, there's usually no legal requirement that bills be sent out in a timely fashion—so businesses can absolutely bill your months or even years after the fact. If it's a medical debt, there's the added confusion of insurance coverage and the challenge of understanding the bill in the first place.
Backdating invoices isn't inherently illegal—but misusing it to manipulate revenue or tax periods risks serious penalties.
What to do if a customer doesn't pay
Under the current guidelines, users must upload invoices within 30 days from the invoice date. If you miss this window, the IRP will reject the invoice, which means it won't be considered valid for GST compliance or for claiming input tax credit.
Typically, businesses should bill for services or products promptly, but there isn't a specific law that prohibits billing for something from over two years ago directly. The statute of limitations for written contracts in California is four years, and for oral contracts, it's two years.
If a customer asks for a tax invoice, you have 28 days to send it.
Generally speaking, contractors should collect payment for services within a reasonable amount of time, and this usually ranges from 30 to 90 days. In many states, payment is required within 30 days of the service being completed.
If the company forgot to bill you, it has four years to collect on the above types of debt or six years if the debt is a promissory note. If the company does not file a lawsuit to collect the debt before the applicable statute of limitations expires, it is too late for the company to collect on the debt.
Common invoice timeframes for payment include 14 days, 30 days, 60 days and 90 days. Typically, the standard term of payment is 30 days or less, but you can choose any amount of time for your term. Online invoicing makes paying faster and easier for customers to pay quicker.
Backdating a contract is not inherently illegal, but it becomes unlawful if it misleads, deceives, or results in financial or regulatory harm. Legal backdating must reflect the actual intentions and actions of the parties involved; otherwise, it can be considered fraud or forgery.
It becomes late or past due the day when the deadline passes and you still have not received payment. Some companies might also set a specific number of days to differentiate the two. For example, one invoice might be considered overdue if it is 30 days past due.
False invoicing may also be considered invoice fraud. This occurs when a business sends an invoice to a customer to pay for goods or services that the business is aware that the customer did not purchase.
The short answer is for most debts, that limit is 6 years.
The Act explains that you have 6 years to chase those elusive payments before they become statute barred, which means that you are unable to use legal action to provoke payment.
In California, for instance, providers have one year from the date of service to submit claims, which allows for some variation in billing precision and adjustments.
The general rule is that if it becomes necessary to issue legal proceedings to recover an unpaid invoice, then the creditor must do so within the statutory time limit of six years from when the clock starts to tick.
30-day e-invoicing upload rule: Businesses with an AATO of ₹10 crore or more must upload their e-invoices to the IRP within 30 days of the invoice date (effective from April 1, 2025), after which the system will reject them.
Filing a Lawsuit for Breach of Contract
If your client agreed to pay for goods or services and failed to follow through, they may be in breach of contract. You have the right to sue for the amount owed, and possibly additional damages, depending on your contract and the impact of the missed payment.
If you have an unpaid invoice, here are some steps you can take to try and resolve the situation: