The anchor problem: why a payment deadline is usually wrong at its start date, not its number

Published 18 October 2026 · Updated 18 October 2026 · By Oliver Stocks-Fryer

Payment law across the UK, Switzerland and Europe is a number of days plus an anchor, the event the days count from. What the anchor is, why the EU Late Payment Directive puts the same trap in every member state, what we found when we checked our own engines, and what to record so a due date stands up.

A flooring subcontractor in Milan invoices a stage on 1 March for screed that goes down on 20 March. The contract fixes no payment date. Count thirty days from the invoice and the money is overdue from 31 March. Count it the way Italian law does and it is not due until 19 April, because where the invoice reaches the client before the work is done, the thirty days run from the work. Chase on 1 April and you are chasing money that is not late yet, and any interest you claim starts on the wrong day.

The thirty was right. The day it counted from was wrong. That is the anchor problem, and it is the most common way a payment deadline goes wrong anywhere in Europe.

What is the anchor of a payment period?

The anchor is the event a payment period counts from: the invoice reaching the client, the work being done, an acceptance or verification, the end of a valuation period, or a notice. Every payment rule has two parts, a number of days and an anchor. The number is printed in the statute and almost nobody gets it wrong. The anchor sits in the sentence around the number, often with a fallback for when the obvious anchor does not apply, and that is where the mistakes are.

What did we find when we checked our own engines?

VariationFlow has payment engines for subcontractors in seventeen markets, each written from that country’s own statute, though only the UK and Switzerland are open so far. When we checked those engines against the statutes in September 2026, the day counts were almost always right and the anchors were not. Spain, Italy, France and Poland all counted from the invoice where the law counts from the work. We then went back over three countries we had already signed off, the Netherlands, Belgium and Austria, and found the same thing in all three.

None of those markets had opened, so no customer was given a wrong date. But the error ran the same way every time: an invoice raised ahead of the work made the money look overdue before it was. A test that checks arithmetic cannot see that, because the arithmetic is right. Two of the engines even had the right rule written in a comment, addressed to whoever called the function, and nobody had.

Why does every EU country have the same trap?

Because they share a source. The EU Late Payment Directive, 2011/7/EU, sets the default where a business contract fixes no payment date: thirty days from the debtor’s receipt of the invoice. Article 3(3)(b) then moves the start in three cases. Where the date the invoice arrived is uncertain, or the invoice arrived before the goods or services, the thirty days run from receipt of the goods or services. Where there is an acceptance or verification procedure and the invoice arrived no later than its end, they run from the acceptance or verification. Article 4(3)(b) says the same for public authorities.

Every member state wrote that into its own law in its own words, so the same rule turns up with a different article number in each country. A construction invoice raised at the start of a valuation period, before the work in it is finished, is exactly the case the fallback was written for, and it is the ordinary case on site.

Where is the rule in each country?

• Spain: article 4.1 of Ley 3/2004 counts the thirty days from the performance, even where the invoice arrived earlier. The invoice is not the primary anchor at all.
• Italy: article 4, paragraph 2 of Legislative Decree 231/2002 is a four-way cascade, and letter c) is the one that matters on site: where the invoice arrived before the work, the thirty days run from the work.
• France: article L441-10 I of the Code de commerce gives thirty days from the performance where no term is agreed, and caps an agreed term by reference to the invoice. Each rule has its own anchor.
• Poland: article 7(4) of the Act on counteracting excessive delays in commercial transactions runs the term from receipt of the work where the invoice’s delivery date cannot be established or the invoice arrived first.
• The Netherlands: article 6:119a(2)(b) of the Civil Code does the same where no payment date was agreed.
• Belgium: article 4 § 1, first paragraph, 2° of the Act of 2 August 2002 does the same, and the Act also forbids fixing the invoice receipt date by contract.
• Austria turns it round. Under § 1334 of the Civil Code, absent agreement, payment is due without undue delay after performance, or after acceptance or verification where one was agreed, and the invoice is the anchor only where the amount was not yet fixed.

Do the UK and Switzerland have the same problem?

Not the Directive’s version, but both have anchors that catch people. Under the Construction Act and the Scheme for Construction Contracts, the due date for a periodic payment is the later of seven days after the end of the payment period and the date of the payee’s claim. The payment notice, the pay less notice and the final date all hang off that due date, so a wrong due date moves every one of them. Then the counting has its own trap: section 116 leaves out Christmas Day, Good Friday and bank holidays but not weekends, so a deadline can fall on a Saturday and stand, and Northern Ireland counts the same numbers a different way. How days are counted sets that out.

In Switzerland the anchor that catches people is the one for interest. Under the Code of Obligations a debtor is in default only once warned (OR Art. 102 Abs. 1), unless a fixed date was agreed. Default interest is then 5% under OR Art. 104 Abs. 1, unless the contract incorporates SIA 118, where Art. 190 Abs. 1 applies instead and interest runs only from the reminder, at the rate that article sets. On such a contract the thirty days are a payment period and any agreed discount is lost when they expire, but nothing starts interest on day thirty-one. And the four months for registering a builder’s lien under ZGB Art. 839 Abs. 2 run from completion of the work, not from the final invoice. Where the land belongs to a public body’s administrative assets and cannot carry a lien, Abs. 4 puts a statutory guarantee in its place, provided the owner’s liability does not arise from a contract, and that needs a written claim to the owner inside the same four months.

What should you record so a due date stands up?

• The date the work was done, for each stage or valuation period, as well as the date of the invoice.
• The date the invoice actually reached the client, with proof. Where you cannot prove it, several of these laws switch to the work date anyway.
• Whether the contract has an acceptance or verification procedure, and the day it finished.
• On a Construction Act job, the end of each payment period and the date of each application, because the Scheme’s due date is the later of the two.
• In Switzerland, the day the reminder reached the client, because on most contracts interest starts there and nowhere earlier.

How VariationFlow handles it

The fix was to put the rule inside the calculation rather than in a note to whoever uses it. The engines for those seven countries now take the date of performance as well as the invoice date, apply the fallback themselves, and report which anchor they used, so a date says what it was counted from. On UK jobs the payment timeline is reckoned under section 116 by the region the site is in, and on Swiss jobs the reminder letter dates interest from the right event for the contract it is on.

This article is general information, not legal advice. The periods that apply to a job are the ones in your own contract, read with the law of the country the work is in.