Supplier payment due date calculator

Why the submission day matters more than the invoice date

With a private business, a budgeted institution or a local authority, counting starts at the end of the month the invoice was presented in. An invoice submitted on the 1st and one submitted on the 30th land on exactly the same payment date, so holding a finished invoice until month end costs almost a full month of cash flow. With the state, counting runs from the submission day itself, and there every day saved brings the payment a day closer.

So the date printed on the invoice is not what starts the clock. What starts it is the day the invoice reached whoever is meant to pay it, through whatever process was agreed with them.

What you are owed on a late payment

From the due date onward the debt carries index linkage and interest, and 30 days after that, arrears fees are added on top. Both are set by the law and need no clause in the contract and no agreement from the customer. The detail is in the payment terms law guide.

When a different date can be agreed at all

A date later than the default holds only where the payer is a business or a budgeted institution, and only where the nature of the engagement justifies it. With the state the date cannot be varied at all. A contract clause setting net 90 with a government ministry does not make that date lawful, and the statutory date continues to apply.