Neil Simpson is a former Personal Finance Journalist of the Year and the author of the Buy-to-Let Investor column in Financial Mail on Sunday. He is a keen property investor and writes about buy-to-let online as well as for a variety of publications including City AM.

Every buy-to-let investor ought to have a war chest of money put aside for emergencies - and this summer there is both bad and good news on the subject. First the bad news: recent events prove that emergencies can be a lot bigger and more expensive than a broken down washing machine or broken central heating system. Anyone whose property has been hit by the recent flooding is looking at a far larger repair bill or a hefty void period while tenants have to be housed elsewhere. If you’ve got decent landlord insurance you may get some of the money back.

Landlord Mortgages can help explain how these policies work if you’ve not taken one out before. But this isn’t the end of the bad news. Rising interest rates can trigger just as much trouble as rising water levels. If your rental income no longer covers your new repayments you may need to subsidise the property until your current tenancy ends. Then you need to hope the market will stand a decent increase. Fortunately this is where the good news comes in.

Firstly, the market across much of the country looks set to allow some healthy rent increases over the next year. Lettings agents say the era of frozen or falling rents seems to have ended, not least because potential first-time buyers are holding back from buying and increasing demand for rented accommodation. The second bit of good news is that rising interest rates and competition between a new generation of banks means emergency savings can now earn more than have done in a decade.

Bank of England base rate is now 5.75 per cent. Many economists think it may be increased to 6 per cent in August or September. But savers can easily get 6 per cent interest already – sometimes tax free. Even better news is that if you save with the right company you may get a windfall bonus as well. Industry insiders are predicting a new wave of mergers or takeovers in the building society sector. The huge windfall payments we got when the likes of Halifax and Woolwich turned into banks aren’t likely to be repeated. But other more modest windfalls will still make a pleasant surprise.

So here’s a run down of where it can pay to save. If you want a high interest, easy access savings account then you need to stay online. And you need to look beyond traditional banking names. At the moment Sainsbury’s Bank is the best paying provider. You can earn 6.25 per cent gross on balances starting at just £1. Next in the best-buy charts comes IceSave paying 6.2 per cent on £250 or more. IceSave is an Icelandic bank that’s trying to build up a global presence – hence the high rates. It is fully authorised by the Financial Services Authority and it has signed up to the voluntary Banking Code, so you are as well protected as you are with any other provider. The only real risk is that your interest rate might fall fast once the bank has got enough British customers. That’s pretty much what Dutch bank ING Direct did. It had a top rate when it launched in the UK, but in November and January it failed to pass on either of the Bank of England’s two rate rises to customers.

Of the other best-buy firms Birmingham Midshires may look like a windfall possibility as well as a top payer. It offers 6 per cent on its online accounts. But the firm is already part of Halifax so windfalls are out of the question. The little known Principality building society might be different. It offers 5.85 per cent and may one day be a takeover target.

For tax-free savings you need a cash mini Isa. Rates here are even better and windfall prospects can be strong. But check the small print on accounts. You can’t dip into and out of them at will. Once you have paid in the annual maximum of £3,000 you can’t top it back up after any withdrawals.

National Savings & Investments offers the highest profile good deal – it pays 6.3 per cent tax free on £1,000 or more. Tipton & Coseley building society pays more – 6.4 per cent – but you need £3,000 and have to give notice for withdrawals. Another small building society – which capetbaggers and windfall-chasers also love – is Kent Reliance. It offers 6.21 per cent on its cash Isa. Egg, National Counties building society and Leek United building society are also strong cash Isa payers.

If you have an eye on a windfall bonus then there are several other building societies worth considering. With all of them you may still be asked to sign over any windfall to charity if it is paid in your first few years of saving. But those years can pass fast. People who signed up with a raft of societies in 2002 are now past the sign-away point with many accounts and are hoping that they might get lucky.

Experts say many small to medium sized local societies are thought most likely to be taken over – top tips include Cambridge, Chesham, Harpenden, Kent Reliance and Saffron, for example. Catholic building society is also tipped as a target alongside bigger names such as Norwich & Peterborough and Yorkshire. Rumoured mergers between the likes of Chelsea and Coventry or Skipton and Leeds may also pay windfalls. But whether you want a windfall or just an inflation-beating war chest of money the good news is that the rest of 2007 looks a great time to be a saver.