Banks have been forced to come up with all sorts of new wheezes in the last couple of years. In an effort to balance the books a little more effectively, they have had to attract savings from customers before they are able to start lending money a bit more freely. It's a back-to-basics kind of approach: the sort of thing they used to have to do before they hit on the clever notion of inventing money.

However, with savings rates looking decidedly miserable, and everyone struggling to find cash to start a savings account or investment, they are having to be a bit clever about it.

So they have increasingly been bringing in products with strings attached. Santander will join the host of companies offering it next week. So what's the catch, and is it worth it?

The cunning plan is to offer you a market-beating deal, as long as you take out another product from the company concerned. So Santander, for example, is offering a fee-free current account to all customers with a Santander investment product.

First Direct does something similar, but slightly more generous, asking you to take out a credit card or savings plan in order to get a free current account - otherwise it charges £10 a month, unless you pay in at least £1,500 a month.

They are far from alone. The rash of companies offering deals with strings attached means that if you apply for any kind of product, you are likely to be leaned on to get linked products from the provider.

So is this such a bad thing?

As ever, it depends. If you need both products, and they are market-leading, then it's a win-win. However, if you find yourself taking a product you wouldn't otherwise have taken, or you end up accepting a rate you wouldn't otherwise have gone for, then this is a false economy.

Take the First Direct deal, the current cash ISA rate is really very competitive, so if you were looking for a cash ISA to go with your current account anyway, you're onto a winner. If, however, you don't have the money to put aside even a penny in this account, and you are struggling to meet debt repayments as it is, then this could be unwise.

Santander, meanwhile, offers the deal to anyone taking out a product from Santander Investment management, or one of its structured products. This requires a great deal of care. There may be one out there to suit you. However, with all structured products it's vital to understand the downsides.

They offer a percentage of the growth in the stockmarket or the housing market, with a guarantee of your money back if the index falls. However, you are tying your money up for up to five years and if the index falls you could find yourself back where you started. The housing market for one is not guaranteed to have a great five years. In addition, if you are buying something linked to the stockmarket you don't get any dividends. This makes up a huge part of the growth of shares, so it's worth understanding that you'll miss out on this.

As ever, the best advice is to check out the products carefully, make sure you understand them, you can afford them, and that they suit you. Only then might you want to take out a linked product. Otherwise you may prefer to go with a slightly less headline-grabbing option without any strings attached.