Over one-and-a-half million Barclays NISA customers will see their rates drop this autumn as the bank will be moving most of its old NISA customers onto a new deal.

Customers with old Barclays NISAs will be moved to the bank's Instant Cash ISA Issue 1, which launched last March (see our Top Cash NISAs guide for the best buys). The bank is telling customers about the switch by post this week.

The Instant Cash ISA pays 1.29% AER for those with a balance of £1-£14,999, 1.39% AER for those with a balance of £15,000-£29,999 and 1.49% AER for those with a balance of £30,000+.

It also accepts transfers-in of old NISAs and allows customers to access their money in branch, over the phone, online and via mobiles.

Of the 2.4 million customers affected by the move, 1.6 million customers will see their interest rates drop.

Those with a Freestyle Cash ISA, which currently pays 2.8%, will see the biggest fall. Barclays says 95% of customers who will see a drop in interest will lose an average of £2.22/month.

Barclays' Instant Cash ISA rates can also be beaten by other easy-access NISAs currently on the market. See our Top Cash NISAs guide for more.

ISAs were offically renamed NISAs (New ISAs) in July. They allow everyone to put £15,000 into cash or shares savings without paying tax on it. Despite the change, some providers, including Barclays, still refer to their accounts as ISAs.

Who's affected?

These 11 accounts will become Instant Cash ISAs on 5 November:

  • Freestyle Cash ISA (currently pays 2.80% AER).
  • Loyalty Reward ISA (2.03% AER).
  • Direct Cash ISA (1.80% AER).
  • Golden ISA (1.80% AER).
  • Golden ISA Issue 2 (1.80% AER).
  • Golden ISA Issue 3 (1.80% AER).
  • ISA Saver Issue 2 (1.73% AER).
  • ISA Saver Issue 1 (1.51% AER).
  • Tax Haven ISA (0.83% AER).
  • Tax Beater ISA (0.56% AER).
  • Barclays Cash ISA (0.10% AER).

Customers with a Direct Cash ISA Issue 2 aren't affected. This was offered by ING Direct, whose savings and mortgage business was taken over by Barclays last year.

Does the move affect any other T&Cs?

Barclays says the Instant Cash ISA terms and conditions will be the same as the old accounts.

Can Barclays' NISA be beaten?

Yes. If you're after easy access cash to so you can take our money when you want, BM Savings currently pays 1.55% AER, including a 1.05% bonus for a year with a minimum £1 deposit. It also allows transfers of previous years' NISAs, although you can only access the account via post.

Halifax pays 1.5% AER, including a 1.25% bonus for a year, with a minimum £1 deposit. It allows transfers of previous years' NISAs, and you can access the account online.

You can also earn more if you're willing to lock away your cash. See our Top Cash NISAs guide for all the best buys.

Why is Barclays doing this?

Barclays head of savings Lee Chiswell says: "We want to simplify the way we do business with our savings customers. These changes will make it easier for our customers to understand their products, and easier for our staff to serve them. Customers will also have the added benefit of being able to transfer in.

"We are writing to all impacted customers to let them know how these changes will affect them, and we have worked with our colleagues to ensure they can support customers who have any questions about these changes."