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See how much you could save

Mortgage overpayment calculator

What are your options?

Before using the overpayment calculator, take a look at your options for making an overpayment. 

One-off overpayment 

  • This is an additional payment that you can make at any time.
  • You can make one-off overpayments as often as you like, but if you exceed your overpayment allowance, you’ll have to pay an Early Repayment Charge (ERC) on the amount over 20%.   
  • If you pay £1,000 or more, your monthly payment will be recalculated.
  • If you want to pay off your mortgage or you have less than £500 remaining, you’ll need to request a redemption statement by logging in to Manage your Mortgage.

Regular overpayment           

  • This is a regular payment you make every month on top of your monthly Direct Debit.
  • You must continue to make your normal mortgage payment in full each calendar month.
  • If you pay more than 20% of your outstanding balance, we’ll cancel your regular overpayment so that you don’t pay an ERC.
  • Monthly overpayments will reduce your mortgage balance and could help save you interest.
  • You can set-up, amend, or cancel your regular overpayment by logging in to Manage your Mortgage.

Deciding how much to overpay              

  • If you’re on a fixed or tracker rate product, you can pay up to 20% of your outstanding balance for each of your sub-accounts before an ERC will apply. If you exceed your allowance, you’ll have to pay an ERC on the amount over 20%. To find out what this means for you, log in to Manage your Mortgage.
  • If you’re on our Standard Variable Rate (SVR), there’s no limit to how much you can overpay, and there’s no ERC.

Mortgage overpayment calculator

Want to make an overpayment and understand how this could impact your mortgage payments and interest? Pop your details into our simple overpayment calculator and we’ll show you just that. Here are your overpayment options:

Select an option to see how you could save:

A lump sum overpayment can lower your monthly repayments.
Paying a lump sum is a way to lower your monthly payments.
Please enter your mortgage balance

Time Remaining (Years, Months)*

Please enter current interest rate on your mortgage
Please enter extra monthly payments

and/or

Please enter lump sum payment
*This information is required.

Overpayment results

Current monthly repayment:

New monthly repayment:

Amount saved each month:

You could reduce your term by:

Amount of interest you could save:

Important information

If you're not on our Standard Variable Rate (which has no restrictions on the amount you can overpay), there may be a maximum amount you can overpay each year without incurring an Early Repayment Charge. For more information please refer to your most recent mortgage offer.

To calculate your potential savings, we've made the following assumptions:

  • The amount you currently pay is based on the information you've entered.
  • You’ll make the same monthly overpayments for the whole of your mortgage term.
  • The interest rate will remain the same for the term of the mortgage.
  • Months are of 12 equal lengths so the monthly interest won't change.
  • Repayment amounts are rounded up or down to the nearest £1 for display purposes.
  • The potential reduction in time to repay your mortgage is presented as years/months. The figure is rounded up or down accordingly for display purposes.

This calculator should be used as a guide only. It won’t give you a definite figure of how much interest or time you could save paying back your mortgage. It also doesn’t take into account any charges for early repayments and is based on a capital repayment mortgage only. It doesn’t include all the information you need to compare mortgages, so please ask for a mortgage illustration before choosing a mortgage.

Your home or property may be repossessed if you do not keep up repayments on your mortgage.

Frequently asked questions

Log in to Manage your Mortgage

Log in securely with our Mobile App and Online Banking services.

Mobile App

Log in to or download the NatWest app, tap your mortgage when you're in the app and then click 'Manage your Mortgage'. 

Not registered for mobile? That’s fine, you can register using your mortgage account number. If you need any help registering, you can use our guide for mortgage customers.

Online Banking

Mobile App isn't for you? We've got you covered, you can access 'Manage your Mortgage' through Online Banking. You'll need to use your mortgage account number to register for the first time.

You can follow this link to register for Online Banking. If you need any help then you can follow our step by step guide.