Should you fix your mortgage for ever?

Few assets are as political as housing, and therefore few markets depend as much on national borders as those for mortgages. Governments can twiddle endless dials to control what goes on, concerning everything from how much you can borrow and who can lend, to what they can do if you stiff them. For today’s borrowers, though, one dial feels most urgent: how long is your fix?

If you are American or Danish, the answer may well be that you have a fixed interest rate for the duration of your mortgage. As a result, you may pay as little attention as you wish to hawkish central bankers and climbing bond yields. In many other countries—including Britain, Canada and much of southern Europe—mortgage rates tend to be fixed for a few years at most, or not at all. If you fall into this group, you may recently have devoted rather more thought to monetary policy than you would like, since (congratulations!) you are one of its transmission channels. Faced with imminently rising payments, you might be looking enviously at those who need never worry about them.

Things are not as great as they first appear for this group, however. America’s frozen housing market, with homeowners unwilling to sell and lose the low rates they locked in during the cheap-money years, should alert policymakers to the dangers of long-term fixes. For mortgage-payers, there is a more straightforward reason to be wary of such lending. A lifetime rate might offer psychological safety. But it is safety you must pay through the nose to achieve.

To see why, start with how fixed rates are set. Whoever is lending to you—bank, building society or bond investor—is either borrowing the money themselves (from depositors, say) or forgoing lending it to someone else (such as by buying government bonds). In both cases they are giving up interest payments elsewhere. Your mortgage rate needs to compensate for this if they are to lend at all. One compensation method is a rate that floats on market conditions, always matching the interest payments the lender is losing elsewhere. The other is a rate that is fixed for a set number of years, at the average funding cost the lender expects over the course of the period.

The catch is that you might want to repay your mortgage early—to move house, for instance. On a floating rate, the lender is unlikely to mind. After all, they are able to take your repayment and lend it to someone else for the same income. But on a fixed rate, they may mind considerably. Suppose you originally agreed to pay 5% interest for 30 years, then want to pay it back at a time when the equivalent market rate has fallen to 3%. In such a scenario, your lender will no longer be able to lend out your repayment for anything like the same income. Again, they will want compensation: the two-percentage-point difference, multiplied by the however-many years left on the mortgage, multiplied by your average remaining balance. A lot, in other words.

Hence the unpopularity of 30-year fixed rates in much of the world. Few borrowers want to risk huge prepayment costs if their circumstances change and markets have moved in the wrong direction. One solution is for regulators to cap costs, but this just discourages lending on long-term fixes in the first place.

Next to this, the alternative solution adopted by America and Denmark seems almost like alchemy. In both countries, mortgages can be fixed for 30 years and are prepayable at face value at the borrower’s demand. Americans experience no profit or loss regardless of how rates have moved. Danish borrowers similarly pay no penalty if rates have fallen (making their fixed rate expensive by comparison) but can realise a profit if rates have risen. This means that, unlike Americans, Danes need not worry about surrendering a cheaper-than-market rate to move, and can do so more freely.

Yet there is a price for everything, and in this case the price is eye-wateringly high borrowing costs. The average rate on a new, 30-year American mortgage stands at 7.2%, whereas the 30-year Treasury rate is just 4.4%. In Denmark the equivalent rates are 5.3% and 2.9%. In Britain, meanwhile, borrowing costs for mortgage-holders and the government are broadly similar. Put differently, both long-term fixes add more than a third to each of the 360 monthly mortgage repayments in question. Those who had the enviable foresight to secure rock-bottom rates a couple of years ago may not mind much. Everyone else, no matter how envious, should remember that safety doesn’t come cheap.■

Read more from Buttonwood, our columnist on financial markets:
High bond yields imperil America’s financial stability (Aug 29th)
Why investors are gambling on placid stockmarkets (Aug 17th)
In defence of credit-rating agencies (Aug 10th)

Also: How the Buttonwood column got its name