More than 400,000 National Savings & Investments (NS&I) Isa customers will see the interest on their Isas slashed in mid-November.The rate on the NS&I Direct Isa will fall by 0.25 percentage points to 1.25% on 16 November.According to the Bank of England, average rates received on instant access Isas have fallen from 1.09% to 1.01% over the year to August. Jane Platt, chief executive at NS&I said: "Interest rates in the easy access ISA market have been in decline over the year and our Direct ISA rate has stood out at the top of the best buy tables for some time."To ensure that we continue to strike a balance between the needs of our savers, taxpayers and the stability of the broader financial services sector, we have taken the difficult decision to reduce the rate on our Direct ISA." Where can I find the best instant-access Isa rate?The Direct Isa was one of the best instant-access accounts on the market, though a handful of providers currently offer better terms. If you can find a branch to open an account, the Punjab National Bank pays 1.65% AER on balances over £1. The bank has seven branches in the UK, in Central London, Southall, Leicester, Birmingham, Illford, Wembley and Wolverhampton.Danske Bank pays 1.6% AER on balances over £30,000, but just 0.4% on smaller deposits. You can transfer cash Isa savings into the account, which can be opened in-branch or over the phone.If you're looking to save regularly, the Buckinghamshire Building Society Chiltern Golden Nuggets account (issue 4) pays 2% AER on balances over £10 if you pay in regularly. You can open the account in branch or by post. You're just allowed one interest-free withdrawal per year, otherwise the interest rate plummets to 0.1% AER.