Stop Being a Free Bank
Late payments are the number one killer of small businesses. When a large corporate client delays your payment by 60 days, they are actively using your money to fund their own operations while starving you of cash flow.
By calculating and enforcing a statutory interest penalty, you change the dynamic. Once a client realizes that delaying your payment will cost them an extra 10% in fees, your invoice suddenly moves to the top of their accounts payable pile. It is not about greed; it is about establishing boundaries and ensuring you are paid on time.
How to Collect the Fees
Calculating the interest is only the first step. To actually collect the money legally, you must follow a strict paper trail:
- Calculate the Total. Input the original invoice amount, the exact due date, and your annual interest rate into our calculator. If you don't know the rate, 18% is a common B2B standard.
- Draft an Official Notice. Use our business letterhead generator to write a formal letter notifying the client that their account is past due and that interest has been applied according to your terms.
- Issue a New Document. You cannot simply change an old invoice. You must issue a debit note that explicitly bills them for the late fees and references the original invoice number.
Preventing Late Payments Proactively
Chasing down debt is exhausting. The best way to deal with late payments is to prevent them from happening in the first place by setting clear expectations early on.
Before you even start a project, make sure your late fee policy is clearly outlined in a signed service agreement. If a client signs a contract agreeing to an 18% annual penalty for late payments, they cannot argue with the math later.
Additionally, consider using the carrot instead of the stick. Instead of only punishing late payers, use our early payment discount calculator to offer a 2% reward for clients who pay within 10 days. Many businesses will rush to pay you just to secure the discount.
Frequently Asked Questions
Am I legally allowed to charge late fees?
In most countries, yes. If you are a business selling to another business (B2B), laws usually give you a statutory right to charge interest on late payments, even if you didn't explicitly write it in the contract.
What interest rate should I charge?
If you have a signed contract, use the rate specified there. If not, use the statutory rate for your jurisdiction. For example, the UK allows 8% plus the Bank of England base rate. In the US, it varies by state, but 1.5% per month (18% annually) is a common standard.
How does the calculator figure out the interest?
It uses a simple daily interest formula. We take your annual interest rate, divide it by 365 to find the daily rate, multiply it by the original invoice amount, and finally multiply that by the number of days the invoice is overdue.
What is a fixed late fee?
Some regions allow you to charge a flat, fixed fee for the administrative cost of chasing down the debt, on top of the percentage-based interest. You can enter that amount in the fixed fee box.
How do I ask the client to pay this?
You should not just send an email. You need to officially document the new charges by sending them a debit note, which acts as a formal addition to the original invoice.