Bank of England Base Rate and Late Payment Interest
The Bank of England base rate is an important part of many UK late payment interest calculations. For many business-to-business overdue invoices, statutory interest is commonly calculated using the Bank of England base rate plus 8%.
This means that when the base rate changes, the annual interest rate used for some late payment calculations may also change. Understanding how the base rate works can help businesses estimate interest on overdue invoices more clearly.
This guide explains what the Bank of England base rate is, how it relates to late payment interest, and how it may affect overdue invoice calculations.
What is the Bank of England base rate?
The Bank of England base rate is the interest rate set by the Bank of England. It influences many interest rates across the UK economy, including savings rates, borrowing rates, mortgage rates, and some commercial interest calculations.
For businesses dealing with overdue invoices, the base rate matters because statutory late payment interest is often calculated by adding 8% to the Bank of England base rate.
For example, if the Bank of England base rate is 5.25%, the statutory annual interest rate may be:
5.25% + 8% = 13.25%
This annual interest rate can then be used to calculate interest on an overdue invoice.
How does the base rate affect late payment interest?
The base rate affects late payment interest because it forms part of the annual rate used in many statutory interest calculations.
The common formula is:
Statutory interest rate = Bank of England base rate + 8%
Then the late payment interest can be estimated using:
Invoice amount × annual interest rate × number of overdue days ÷ 365
This means there are three main inputs:
The unpaid invoice amount
The annual interest rate
The number of overdue days
If the base rate increases, the statutory annual interest rate may also increase. If the base rate decreases, the statutory annual interest rate may also decrease.
Example calculation using the base rate
Here is a simple example.
Invoice amount: £1,000
Bank of England base rate: 5.25%
Additional statutory rate: 8%
Days overdue: 30 days
First, calculate the annual statutory interest rate:
5.25% + 8% = 13.25%
Then apply the late payment interest formula:
£1,000 × 13.25% × 30 ÷ 365
Convert 13.25% into a decimal:
13.25% = 0.1325
Then calculate:
£1,000 × 0.1325 × 30 ÷ 365 = £10.89
So, the estimated late payment interest would be:
£10.89
The estimated total amount including interest would be:
£1,010.89
Why the base rate can change the result
The Bank of England base rate can change over time. Because statutory interest may use the base rate as part of the calculation, the interest amount on an overdue invoice can also change depending on the applicable rate.
For example, on a £1,000 invoice overdue by 30 days:
If the base rate is 4.00%, the annual rate would be 12.00%.
If the base rate is 5.25%, the annual rate would be 13.25%.
If the base rate is 6.00%, the annual rate would be 14.00%.
Using the same invoice amount and overdue period, a higher base rate would usually produce a higher interest amount.
This is why businesses should check the relevant base rate before calculating statutory interest.
When should you check the base rate?
You should check the Bank of England base rate when you are calculating interest on an overdue invoice and the calculation depends on the statutory rate.
This is especially useful when:
An invoice has been overdue for a long time
The base rate may have changed recently
You are preparing a payment reminder
You are estimating interest before contacting a customer
You want to understand how much may be added to the invoice
Because the base rate can change, using an outdated rate may produce an inaccurate estimate.
Use a calculator for quicker estimates
If you want a quicker estimate, you can use our UK Late Payment Interest Calculator to calculate interest based on the invoice amount, due date, payment date, and interest rate.
A calculator can help you estimate:
The number of overdue days
The annual interest rate
The daily interest amount
The total estimated interest
The total amount including interest
This can reduce manual calculation mistakes and make it easier to understand how the base rate affects the final amount.
Bank of England base rate vs total statutory rate
It is important not to confuse the Bank of England base rate with the total statutory interest rate.
The base rate is only one part of the calculation.
For many UK business-to-business late payment calculations:
Total statutory rate = Bank of England base rate + 8%
For example:
Base rate: 5.25%
Additional rate: 8%
Total annual rate: 13.25%
The total annual rate is the percentage used in the late payment interest formula.
Does the base rate always apply?
The Bank of England base rate is commonly relevant for statutory late payment interest in many UK business-to-business situations. However, it may not apply in every case.
Some contracts may include their own late payment interest terms. This is known as contractual interest. If a contract clearly states a different interest rate or payment arrangement, the contractual terms may need to be considered.
Other situations may also depend on the type of invoice, the parties involved, and the terms agreed between them.
For this reason, businesses should always check their contract, invoice terms, and relevant guidance before adding interest.
How the base rate connects to the late payment interest formula
The base rate is linked to the formula because it helps determine the annual interest rate.
The formula is:
Invoice amount × annual interest rate × overdue days ÷ 365
If statutory interest is being used, the annual interest rate is commonly:
Bank of England base rate + 8%
So, if the base rate changes, the annual interest rate changes, and the final interest amount may also change.
You can read more about the calculation method in our UK Late Payment Interest Formula Explained guide.
Important points to remember
The Bank of England base rate can affect statutory late payment interest.
For many UK business-to-business invoices, statutory interest is commonly calculated at the Bank of England base rate plus 8%.
The total annual rate is used in the daily interest formula.
The number of overdue days also affects the final amount.
A higher base rate usually means a higher interest estimate.
Contractual interest terms may apply instead in some situations.
Always check the relevant rate and contract terms before adding interest.
Final thoughts
The Bank of England base rate plays an important role in many late payment interest calculations. When combined with the additional 8% used in many statutory interest calculations, it helps determine the annual interest rate applied to overdue invoices.
Understanding the base rate can help businesses estimate late payment interest more accurately and avoid using outdated figures. For quick estimates, using a calculator can make the process simpler and reduce the chance of calculation errors.
This article is for general information only and does not constitute legal or financial advice.