Banks are offering interest rates available below 5 per cent across most loan terms.

For six-month terms, ASB and BNZ have the best rate of the major banks, at 4.99 per cent.

Fix for a year and you can get 4.35 per cent from ASB and BNZ.

The best two-year rate is 4.39 per cent from BNZ. If you want a longer term, try HSBC's 4.49 per cent or ASB's 4.79 per cent for three years. For a five-year term you can't go past ASB's 5.09 per cent.

Some of these are special rates and require equity of 20 per cent or more.

As little as five years ago, this would have been unimaginable.

Banks' special offers grab headlines as they compete for market share.

But they should also serve as a reminder to all homeowners to regularly check their mortgages.What suited you when you took a loan out might not be the best arrangement now.

Are your loans structured in the best way for your circumstances? Might a revolving credit account allow you to offset some of your interest costs? These are good questions to ask an expert mortgage adviser or your bank manager.

If you're on a tight budget, lower rates might make your loan more affordable and give you a bit of breathing room.

But if you now have a bit more money to spare than you did when you first bought your house, this is the perfect chance to slash your mortgage.

Grab one of the low rates – they are all low by historic standards so you can't really go wrong – and bump up your payments a bit to what you were paying just a few years ago when rates were 6 per cent or 7 per cent. You could be amazed at the years you can take off your mortgage.

If you are still floating, waiting for the right time to act, consider fixing at least some of your loan.

Reserve Bank statistics show there are almost 630,000 mortgages worth $52.1 billion, on floating rates. At best, they might be paying 5.9 per cent. In some cases you can shave a full percentage point off your rate just by fixing. Collectively, that's worth $521 million in payments a year.

Take the opportunity to do a mortgage health check. Any decision you make could have lasting long-term consequences.