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When is this invoice actually due?
Net terms run from the invoice date unless the contract says otherwise, and "net 30" is thirty calendar days, not a month. Getting this wrong by a couple of days is the commonest reason a chase email lands before it should.
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What Net 30 actually means
Net 30 means the full invoice amount is payable thirty calendar days from the invoice date. Three things follow that people get wrong.
It is thirty days, not a month. A Net 30 invoice dated 31 January falls due on 2 March in a common year, not 28 February. If you want the last day of a month, use one of the end-of-month variants instead.
The clock starts at the invoice date, not at delivery, unless the contract says otherwise — and plenty of contracts do. Statutory schemes often pick a later trigger deliberately: Texas makes a payment by a governmental entity overdue on the 31st day after the latest of delivery of the goods, completion of the service, or receipt of an invoice, under Tex. Gov't Code Ann. § 2251.025, and the federal Prompt Payment Act generally runs from receipt of a proper invoice. If your terms are silent on the trigger and you invoice long after delivery, expect an argument about which date started the count.
“Net” means the undiscounted amount, as distinct from an early-payment discount — which is why you see terms written as 2/10 Net 30: two percent off if paid within ten days, otherwise the whole amount at thirty. The discount window and the due date are separate deadlines.
Due on receipt is the other end of the scale: payable when the invoice arrives, which is unambiguous as a term and vague as a date, because nothing records when it was received.
The end-of-month variants and where they are used
The alternative family of terms anchors to the month rather than the invoice date.
- EOM — end of month. The count starts at the last day of the month the invoice was issued in rather than at the invoice date. Net 30 EOM on an invoice dated 3 April runs from 30 April.
- Net monthly account — everything invoiced in a month falls due on one date in the following month.
- Proximo terms, written as “15 MFI” or “the 15th prox” — due on a fixed day of the following month whenever the invoice was raised.
The logic is administrative. A supplier billing the same customer many times a month does not want thirty separate due dates; month-anchored terms collapse them into one payment run. Hence their use in trade supply, wholesale distribution and agency billing, and their rarity in one-off project work.
What they cost you is float, and the amount is not fixed. An invoice raised on the 2nd under Net 30 EOM is effectively on fifty-eight-day terms; the same terms on an invoice raised on the 30th are near enough thirty days. Issue early in the month under EOM terms and you are extending materially more credit than the headline number suggests. Run both variants for the same invoice date and the gap is visible immediately.
Calendar days versus business days
The calculator counts either, and the rule for choosing is blunt: count business days only if the contract says business days. Absent that word, the default reading of “30 days” is thirty calendar days, and asserting a business-day count your terms do not support will be rejected.
The difference is not marginal. Thirty business days is about six calendar weeks before any holidays. Terms written in business days are systematically longer than they look, which is why some payers prefer them and why suppliers should think before agreeing.
Where business days are specified, the next question is whose holidays. Federal holidays, state holidays and a company's own closures are three different lists, and a contract saying “business days” without naming a calendar has left a gap. Statutes that use business days tend to define them: New Jersey's residential grace-period provision excludes Saturdays, Sundays and state or federal holidays. That is a residential tenancy rule, not a commercial one, but it shows a legislature closing the gap private drafting usually leaves open.
Some schemes also vary the count by who is paying. Under the Texas prompt-pay provision a political subdivision whose governing body meets monthly or less often gets 46 days instead of 30, and a vendor who receives payment must pay its subcontractor within 10 days, with the amount overdue on the 11th. If you sit in a chain, your due date and the one above you are different dates.
Weekends, bank holidays and the day money actually arrives
A due date is a legal deadline; settlement is a banking event. The gap between them is where a great many avoidable late payments live.
An ACH transfer initiated on the due date does not usually land the same day. Standard ACH is a batch system that settles on a following business day, and banks do not process on weekends or federal holidays — so a payment sent on the Friday of a long weekend commonly posts on the Tuesday. Cards and instant-payment rails behave differently, and a wire sent before the cut-off can settle same day, but the ordinary case in business payment is that initiating on the due date means arriving after it.
If you are paying, work backwards from the due date by a business day or two and diarise that date. If you are being paid, decide whether your terms mean initiated-by or received-by and write it down; both are defensible, but only one is what your terms currently say.
Weekend due dates need a stated rule too. Many contracts push a due date falling on a weekend or holiday to the next business day; many say nothing, in which case the date stands and the payer is late through arithmetic alone. One sentence — if the due date is not a business day, payment is due on the next business day — removes an entire category of dispute at no cost.
Chasing it, in order
Collection is a sequence, and starting in the wrong place costs you money or the relationship.
- Before the due date, confirm the invoice is in the system. Most late payments are not refusals; they are invoices sitting unapproved, addressed to someone who left, or missing a purchase order number. A check a week out catches nearly all of it.
- On the day after, send a factual reminder: invoice number, amount, due date, days overdue, how to pay. No escalation in the tone yet.
- A week out, find the human. Accounts payable is a queue; the person who ordered the work can usually move things in it.
- At two to four weeks, escalate in writing, stating that interest is running, if it is, and the term it runs under.
- Beyond that, decide: formal demand, a collection agency, or a claim — priced against the amount, because the cost of pursuing a small invoice exceeds it more often than people admit.
Step four is where the due date earns its keep. Interest generally starts running the day after payment was due — that is expressly how New York's private-construction prompt-pay provision works under N.Y. Gen. Bus. Law § 756-b, and it is the ordinary contractual pattern too. Knowing the exact date the clock started lets you state a fee accurately rather than approximately, and an accurately stated fee is harder to argue with.
For the fee itself, and what rate you may charge in the first place, use the invoice late fee calculator; what each state supplies when a contract is silent is in the state-by-state reference. This is general information, not legal advice.
Frequently asked questions
Does Net 30 start from the invoice date or the delivery date?
From the invoice date, unless the contract says otherwise. That default is worth checking rather than assuming, because statutory schemes frequently choose a later trigger and some contracts copy them. The Texas prompt-pay provision for governmental entities starts the count at the latest of delivery, completion of the service, or receipt of the invoice. The federal Prompt Payment Act generally runs from receipt of a proper invoice. If you invoice well after delivery and your terms do not name the trigger, you have created an argument about which date the clock started on, and the arithmetic will not settle it.
What is the difference between Net 30 and Net 30 EOM?
Net 30 counts thirty calendar days from the invoice date. Net 30 EOM counts thirty days from the last day of the month the invoice was issued in, so an invoice dated 3 April runs from 30 April and falls due at the end of May. The practical effect is that EOM terms give more credit the earlier in the month you invoice — an invoice raised on the 2nd is effectively on fifty-eight-day terms, one raised on the 30th on roughly thirty. Month-anchored terms exist to collapse many invoices into a single payment run.
If the due date falls on a weekend, when is payment actually due?
Whatever your contract says, and most contracts say nothing. Absent a stated rule the date stands, and a payer who waits until Monday is late by the terms even though no bank was open. Many contracts add the obvious fix: if the due date is not a business day, payment is due the next business day. Add that sentence and the problem disappears. Separately, remember that standard ACH settles on a following business day and banks do not process on weekends or federal holidays, so a payment initiated on the due date routinely arrives after it.
Should I write my terms in business days?
Only if you mean it, and only if you define it. Thirty business days is roughly six calendar weeks before holidays, so business-day terms are materially longer than the same number of calendar days — which is why payers like them and suppliers often should not. If you use them, say whose calendar applies: federal holidays, state holidays and company closures are three different lists, and “business days” alone does not pick one. On the reading side, never count business days unless the word appears in the terms; the default meaning of thirty days is thirty calendar days.