American Express will hit tens of thousands of cardholders with a £36 annual fee or interest rate hikes in the new year.

Those faced with increases can reject them as long as they notify Amex before the jump comes into effect on 23 February (see the Credit Card Rewards and Reject rate-jacking guides).

The lending giant is in the process of a mass mailout to affected cardholders. Those hit are primarily customers with the Green Membership Rewards or Gold Cashback cards as both types of plastic will be shut down.

Green Membership Rewards cardholders, who pay no annual fee at present, will primarily be moved to the Platinum Membership Rewards card, which has a £36 annual fee.

Gold Cashback credit card holders will mostly be moved to the Platinum Cashback credit card.

In addition, some Blue Cashback credit card customers will also switch to Platinum cashback, even though the Blue card is not disappearing.

Many may benefit from this change as the Platinum card pays up to 1.25% cashback, compared to the up to 1% rate available to Blue card holders.

Amex says while the scenarios above are the most likely transfers, customers may be moved to other cards within its portfolio.

In addition, Amex is upping the interest rate paid by many users.

The new costs will depend on the card they move to and their circumstances. So those most likely to be hit by rises are cardholders moving to a more expensive plastic or users who have a patchy credit history.

How to reject the hikes

You simply need to contact Amex and ask to continue paying current rates but that means you won't be able to spend on the card again.

Amex has agreed to honour any request to continue paying existing rates as long as that is made by 23 February.

Remember, there may be better credit cards available for your circumstances so this overhaul could be your trigger to ditch and switch (see the Credit Card Rewards, Cashback Credit Cards, Best Balance Transfers and 0% Credit Cards guides).

The lender says it "reviews its card portfolio on an on-going basis".

An Amex spokesman says: "We have reviewed the number and range of cards we offer customers and have taken the decision to consolidate our existing portfolio. This has resulted in the closure of some of our existing products and the migration of some card members from one product to another.

"In addition, we have consolidated the range of interest rates and annual fees we charge across our portfolio which has resulted in changes in APRs and annual fees for some of our cards."

Amex refuses to confirm how many card holders will see hikes but the number is understood to be in the tens of thousands.

Further reading/Key links

Cut credit card debt: Best balance transfers, Reject rate-jacking
Get more: Credit Card Rewards