This is an urgent warning. The cash ISA year ends on April 5 and if you don’t use it, you lose it. Yet if you've any savings, your cash is still better in an ISA. As it can take time to open one, you need to act NOW.

Normally, this time of year is called ISA season, because big providers push out hot deals to take advantage of the lurch towards grabbing tax-free savings.

This year, as with all savings now, rates are disappointing. The problem is the government ‘Funding For Lending’ scheme is pumping cash to banks to lend out, so they don’t need money from savers. Of course, things could improve, but don’t hold your breath.

1. They’re not fancy, they’re just tax-free savings accounts

Cash ISAs aren't complex. Everyone over 16 can save £5,640 PER tax year in them. Once in, the interest you earn is safe from the taxman. Crucially, you don’t need to lock cash away. Easy-access cash ISAs let you withdraw whenever you want.

2. Once in, it stays tax-free, year after year

Even with today's dismally low rates, getting cash in each year’s ISA is crucial. Once in, it's permanently protected from tax, so you can gradually protect more and more from the taxman.

Those fortunate enough to have filled their cash ISA every year since they started in 1999 could have £70,000 saved tax-free now.

3. At 2.5% tax-free, it can equal 5% savings

In normal savings, interest is taxed so a basic taxpayer loses 20%, higher 40% and top 50%. In cash ISAs, you keep it all. To match the top 2.5% deal, a basic taxpayer needs normal savings at a massive 3.12%, higher rate 4.17% and top rate 5%.

4. Use it by 5 April or you LOSE IT

Once midnight bongs on 6 April, the current tax year's allowance vanishes like Cinderella. So if you have cash, do it now. Admittedly, the next day you get a new allowance, so you may ask "what's the rush?"

Well, even if that's more than enough, play safe, and put it in THIS YEAR in case you get an unexpected windfall next. Reading this after 5 April? Last year's deadline's passed, but you've now a new, bigger £5,760 allowance.

5. You may be unable to open the best rates right now

While the ISA year ends on 5 April, many providers shut their doors earlier. Below I’ve listed the best rates, but you may find it's not possible to get them by the time you try. Yet the key is to get your money in, preferably at the top rate, but even if not, just anywhere. Then you can transfer it straightaway to boost your rate. There’s a full day-by-day guide to the best rates STILL AVAILABLE at www.moneysavingexpert.com/cashISAs

6. Best buy easy access cash ISA 2.5% AER

If you want to withdraw money whenever, you need an easy access deal. These are all variable rate though, meaning you should monitor the rate as it could drop and if it does ditch and transfer (see point 8 below).

Currently Santander (http://www.santander.co.uk/isa), min £2,500, is the top pick, paying 2.5% AER (variable) interest. It’s followed by Cheshire Building Society (www.thecheshire.co.uk/ISAs), min £1,000, and Tesco (Tescobank.com), both paying 2.3% AER.

The Cheshire’s advantage is that 1.8% of that rate is an introductory bonus until October 2014 – while in the past some have ranted about this, in current climes it effectively gives you a useful minimum rate.

7. Guarantee 2.8% for two years

Most people stick money in their cash ISA then don't touch it. If that's you, Santander's Major ISA http://www.santander.co.uk/isa pays a fixed 2.8% for two years (3% for Santander 123 customers), but you can't access your cash during that time.

It also promises a one-off 0.1% bonus if Rory McIlroy wins a golf major in the next two years. This is a bizarre promotional gimmick, but as it's by far the best short term fixed rate cash ISA anyway, who cares.

Of course, the fact your cash is locked away (you can withdraw early but with a big interest penalty) means you are at risk of missing out if other rates rise rapidly at that time. Though, in the short term at least, rates look more likely to drop than rise.

8. Get up to 3% AER if you've old ISAs

You've a right to boost old ISA rates by transferring them. Never withdraw cash to do this, you must ask the new provider to transfer it for you. Unless stated, all the accounts above allow this, but in some circumstances they can be beaten.

Those with substantial existing cash ISAs who bank with the likes of First Direct and HSBC can get better rates. For a full breakdown of the latest, see www.moneysavingexpert.com/ISAtransfers

9. Consolidate old and new cash ISAs to ease hassles

Be under no illusion, to keep ISA rates high, you'll need to transfer every couple of years. Combining old and new into the current top payer makes that easier to do each time, as they can then be moved in one lump.

10. There are stocks and shares ISAs too

If you want to invest rather than save, you can do that in an ISA too, though the tax benefits for basic rate taxpayers are more limited. Investing isn’t my bag though – sites such as www.fool.co.uk can help you with this.