You can invest £7,200 a year in an ISA (up to £3,600 of which can be deposited in a cash ISA) and returns are tax-free, so this annual allowance is well worth taking advantage of. As a result there is always a last minute scramble for ISAs.
If you are planning to open an ISA this year but have yet to do so, there is still time but you will need to check when the application cut-off is as this will vary - particularly if it's a cash ISA you're after.
Follow our top tips on last minute applications to ensure you don't run out of time and lose your ISA allowance.
Top tips:
Get organised
Firstly, check your savings balance and make sure, if you have to, you've given enough notice for withdrawals or transfers without landing any penalties. You can invest up to £7,200 in total - £3,600 in a cash ISA and the remainder in a stocks and shares ISA (alternatively, the full £7,200 can be invested in a stocks and shares ISA).
If you don't really understand what ISAs are and how they work, read our article 'How to choose a cash ISA' and watch our video 'Cash ISAs explained'.
Choose the best ISA for your needs - now
Once you have decided how much you can invest check out the best ISAS on the market. Our comparison tool will help you identify the best deals. For further information, read Kevin Mountford's article 'Get your ISA now - it's your last chance'.
Branch-based applications - why 'popping in' pays
Most banks and building societies are accepting cash ISA applications in branches until the close of business on Friday. Some will be open on Saturday, giving you a bit longer to get your application in. For example, Barclays, RBS and Natwest will be taking applications right through until close of business on Saturday, April 4. Selected major branches of Barclays will be open on Sunday for customers who are able to pay in branch by cash or, if they are an existing customer, by transfer.
The advice is to check first and don't leave it too late - call into your chosen bank or building society as soon as possible as branches are likely to be very busy this week. Be prepared however, as in some cases, you may have to wait or make an appointment.
Apply online - and avoid the queues
Applying online is a good way of avoiding branch queues but don't assume that this guarantees you more time to get your application in.
While many investment houses will accept online applications for stocks and shares ISAs until the last minute, the final deadline for some cash ISAs - even accounts that are Internet only - may be earlier, so do check with your chosen provider. Standard Life for example stopped taking online (and telephone) cash ISA applications March 31.
While Abbey and Bradford & Bingley will not accept online applications from April 1 - you will need to go into a branch after that date. Alliance & Leicester and ING Direct are only accepting online applications until Friday.
However, some providers will process Internet applications right up until the last minute - but only if you're an existing online banking customer. Barclays customers for example, can apply for its Golden ISA, which is paying a market-leading 3.61%, until 11pm on April 5, while Natwest customers can apply for its e-ISA or Cash Plus Isa until midnight.
The midnight deadline also applies to Royal Bank of Scotland's Cash Plus ISA. It's advisable not to leave it right til the last minute though just in case there's a problem and your application doesn't go through properly as you'll have no time to correct the mistake or reapply.
Because final cut-off times vary it is vital that, even if you're wanting to open an internet-only account, you check with the provider and don't assume that you'll be able to apply on Sunday.
Alliance & Leicester and ING Direct will accept online applications until Friday, while Abbey and Bradford and Bingley recommend you call into a branch if you're applying after April 1 to guarantee your ISA is opened successfully. So, do check first - even if it's an online account you are looking to open.
Existing Barclays customers can apply on-line for its Golden Isa up until 11pm on April 5. However, new customers will have to apply online by close of business Friday April 3, or call in to a branch, paying by cash or transfer. Barclays' advice is to check with your branch in advance as appointments may be necessary to ensure an application.
Also, Natwest customers who are signed up to its Internet banking saving can apply online for its e-ISA account right up until midnight on 5 April, as can RBS online customers wishing to apply for its Cash Plus ISA. New customers however for both these banks may only apply online up until 5pm on April 3.

By phone - still possible
Again, the deadline for telephone applications varies depending on the provider. The advice is clear, if you want to apply over the phone, the sooner you do so, the better. Phone lines will be extremely busy this week, so expect long waiting periods and ensure you have all your correct documentation to hand.
Natwest and RBS will take phone applications up until 5pm on April 3 only and with payment by debit card or transfer only.
For anyone applying for a Standard Life Direct Access ISA, telephone and online applications ended March 31 but they will accept branch applications by direct transfer and CHAPS (Clearing House Automated Payment System) and cheques until 5pm Friday.
Postal applications - missed the deadline?
Applications by post are not advised at this late stage. Some banks and societies will honour postal applications if received before close of business on Friday April 3 assuming there are no subsequent problems with payment processing.
The success of your application will depend on how you are paying money into your ISA account - at this late stage you might find your only option is to make a deposit electronically or with a debit card.
If you haven't posted your application yet, send it recorded post as you can't afford for your letter to go astray at this late stage.
Use it or lose it
Finally, remember, if you do not use up your ISA allowance before April 5, you will lose it and therefore miss out on the chance to avoid tax on the interest earned on these savings.
If you do miss the deadline you won't be able to invest the 2008-2009 allowance but a new tax year starts on Monday, so from then you'll be able to invest your 2009-2010 allowance.
If you lose out on this year's tax-break, just make sure you don't lose next year's.
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