The rate of cashback new and existing customers can earn on household bills has fallen from 3% to 2%, but to offset the change the fee on the account has been reduced from £3 to £2 a month.
Customers joining on or after 26 June will also be hit with a new requirement to pay in at least £1,500 a month and register for online or mobile banking, but existing customers won't be affected by this.
The same changes apply to the Royal Bank of Scotland (RBS) Reward account, which is only available to Scottish customers.
Santander vs NatWest: monthly fee
The Santander 123 Current Account charges a £5 monthly fee, which means you have to shell out £60 a year to use it and benefit from the perks.
The NatWest/RBS Reward account fee has dropped from £3 a month to £2 a month from today, which will take the annual cost from £36 to £24 a year.
[ADVERT]At first glance, it's pretty clear which account is cheaper, but to understand which is the most rewarding overall you will need to figure if you will earn enough cashback to cancel out the monthly cost.
Santander vs NatWest: cashback
The Santander 123 Current Account offers tiered cashback up to 3% on a range of household bills you pay by Direct Debit, which gets credited to your account each month.
You can earn 1% on water, Council Tax and Santander residential mortgage repayments (up to £1,000). There's 2% cashback available on gas and electricity bills as well as Santander home insurance premiums. Finally, you can earn the top 3% rate on mobile, home phone, broadband and paid for TV packages.
The NatWest/RBS Reward account offers unlimited 'Rewards' on seven monthly household bills that you pay by Direct Debit, which can only be converted to cash once the balance reaches £5.
From today, you will earn 2% on Council Tax, water, gas, electricity, broadband, mobile & landline and TV packages instead of 3%.
Here's how the two accounts compare on cashback for a range of typical monthly bills now the rate has changed (I've used my own costs for the comparison).
Typical monthly cost
Cashback NatWest/RBS Reward (2%)
Cashback Santander 123 (1/2/3%)
After the fees are considered that will mean I will pocket £62.40 a year by going for the NatWest/RBS deal compared to £18.96 with the Santander offer.
However, if you have a Santander mortgage and a Santander insurance policy as well as the seven other main household bills, the 123 Current Account will pay more.
I don't have a mortgage with Santander or any insurance policies but if I did I would pocket £11.98 a month which over the year would mean I take away a much better £83.76 after the fee.
The Santander 123 Current Account may also be a more rewarding account if you have savings.
It pays 1.5% interest on balances up to £20,000, which means you could earn an extra £300 a year on top of the cashback you get.
NatWest vs Santander: minimum monthly deposit
You need to deposit £500 a month into the Santander 123 Current Account to benefit from the perks.
New customers opening the NatWest/RBS Reward account from today will have to be able to put in £1,500 a month.
The cashback potential of each account will differ depending on the size of your bills.
The Reward account still pays a better rate for Council Tax and water bills, however the 123 Current Account pays more for mobile, broadband and TV bills and both accounts are equally good for cashback on energy bills.
If you don't have any savings, it's probably worth sticking or switching to the NatWest/RBS Reward deal. However, if you have a Santander mortgage and insurance policies and any savings you'd be better off with the 123 Current Account.