How a top-up works
The extra amount is added to the balance and the loan is re-amortised over the remaining term, usually at the current rate.
Because the term does not lengthen, the payment rises by the cost of the extra borrowing.
Worked example
A £12,000 balance at 7.9% with 36 months left costs £375.48 a month. Adding £3,000 raises the balance to £15,000 and the payment to £469.35.
The payment rises by £93.87 and the extra interest is £3,379.35 over the remaining term.
Check the alternatives
Compare the top-up rate with a new loan or a 0% purchase card for the extra spending. A top-up is convenient but not always cheapest.
Ask whether the top-up extends the term or keeps it the same.
Inputs for the car top up loan calculator
Current loan balance
What is left on the existing loan.
Amount to add
The extra borrowing you want on top.
Interest rate (nominal)
The rate on the topped-up loan.
Remaining term
How many payments are left.
CALCULATOR QUESTIONS
Car top up loan calculator questions
Does a top-up extend my term?
Usually not; the extra is spread over the remaining payments, so the payment rises.
How much more will I pay each month?
In the example, £93.87 more for £3,000 extra.
Is a top-up cheaper than a new loan?
Not always. Compare the rate and any fee with a separate loan.
Can I top up if I am in arrears?
Usually not. Lenders require the account to be up to date.