Invoice Due Date Calculator
Enter the invoice value, your payment terms, and how many days since the invoice was raised to see when payment is due and whether it is overdue.
Your inputs
Estimated cost
Days until due
30 days
Invoice status
Not yet due
Assumptions used in this calculator
- Due date calculated as invoice date + payment terms in days.
- Statutory interest accrues from the day after the payment due date.
- Interest rate = Bank of England base rate + 8% per annum.
Other Spark Finance calculators
Calculator questions
When does an invoice become legally overdue?
An invoice is legally overdue the day after the agreed payment due date. If no terms were agreed, the statutory default of 30 days applies under UK law.
What are the most common payment terms in the UK?
Net 30 (30 days from invoice date) is the most common. Net 60 and end-of-month-plus-30 are also widely used. Public sector buyers are required by law to pay within 30 days.
How to get an invoice due date through Spark Finance
- 1
Complete the free calculator above to understand your estimated monthly repayment.
- 2
Click 'Check your eligibility' to start your full application in under five minutes.
- 3
Spark Finance approaches multiple lenders and presents you with competing offers to compare.
- 4
Accept your preferred offer and funds are typically released within 24-72 hours.
Learn more about an invoice due date
How to Improve Your Chances of Getting a Business Loan Approved in the UK
Apr 19, 2026 · 8 min read
What Documents Do UK Businesses Need to Apply for Finance?
Apr 18, 2026 · 6 min read
How to Fund a Management Buyout (MBO) in the UK
Apr 17, 2026 · 9 min read