Q&A: Basel rules on bank capital - who cares?

Bank regulators, accounting definitions and Switzerland sound like a hopelessly dull combination.

But the new rules that have been announced in Basel may be our best defence against a future financial meltdown.

So what's really going on behind the arcane technical language?

What are these new Basel rules about?

The Basel committee is a powerful group of bank regulators that meets regularly to agree risk management rules that affect every bank on the planet.

The latest rules are much stricter, and have been agreed in response to the 2008 global financial crisis.

The most important rule by far is the "capital adequacy ratio", which sets the minimum cushion of capital a bank must keep to absorb losses on their loans.

Are they important?

Yes. Very.

As the BBC's business editor, Robert Peston, points out, the new rules represent "the most important global initiative to learn the lessons of the 2008 banking crisis and correct them".

Banks may need to cut back on their lending in order to comply with the new rules.

And in the long run, the rules should prevent a repeat of the heady credit-fuelled boom seen in the last decade.

What is bank capital?

It is an accounting concept, but a very important one, because it tells you how close a bank is to going bust.

It is the value of everything a bank owns - including all of the loans it has made - minus everything that it owes - including all of the money that you and I have in our cash accounts.

Banks will need much bigger capital cushions to absorb a future financial crash

In accounting-speak, it is the value of the bank's assets minus its liabilities.

When a bank's assets are worth less than its liabilities, it is insolvent - it cannot pay its debts - and should be shut down.

So the more capital a bank has, the more losses it can take on its loans before it goes bust.

How do they calculate this capital adequacy ratio?

It is the value of the bank's capital as a percentage of its assets.

The ratio tells you what percentage of losses the bank can take on its loans before it goes bust.

Regulators "risk-weight" the assets to calculate the ratio.

This means they ignore ultra-safe investments like cash, but heavily weight risky investments, like a loan to a struggling company.

Under the new rules, the risk-weightings are being made more cautious, especially for the complex financial transactions that were at the heart of the crisis.

What is the new ratio?

There are actually several ratios, depending on exactly how the bank's capital is defined.

The most important - and the strictest - is the "core capital" ratio.

It will rise more than threefold, from 2% currently, to 7% - although there are "buffers" that allow for flexibility in this number.

In simple terms, if a bank has £2 of capital, it can currently make a maximum £100 of loans.

In future, it must either increase its capital to £7, or else cut its lending to £28 (because £2 is 7% of £28).

What about these "buffers"?

The 7% ratio includes a 2.5% "capital conservation buffer".

This means that in a crisis, a bank will be allowed to let its capital ratio drop temporarily to as low as 4.5%.

But then the bank will be limited from paying bonuses and dividends until it has rebuilt its ratio back to 7%.

There is also an extra 2.5% "countercyclical" buffer that will allow regulators to raise the capital requirement to 9.5% during boom times in order to slow down lending.

So does this mean banks will have to keep more of their money in cash?

Northern Rock failed because it was insolvent, not because it ran out of cash

Not necessarily.

People commonly confuse capital adequacy with "liquidity" - that is, a bank's ability to get hold of ready cash.

These days, so long as a bank is solvent, it should always be able to borrow cash during a financial crisis from its central bank, who will act as "lender of last resort".

This was an important lesson from the 1930s, when bank runs - sudden cash withdrawals by panicky depositors - brought down many healthy banks, because their money was tied up in loans, so they simply ran out of cash.

The Basel committee has also set new, stricter rules on how much money banks must keep in cash. But this is a separate issue from bank capital.

Then how will banks meet the new capital rules?

A bank has three choices:

• It can issue new shares. This gives the bank more money without adding to its liabilities, adding to its capital

• It can choose not to pay dividends. Profits not paid out to shareholders are included in its capital

• Or it can cut back on lending and make less risky investments. This will reduce its risk-weighted assets, improving its capital adequacy ratio.

How soon do the banks have to do all this?

Deutsche Bank's Josef Ackermann was one of the first to announce plans to raise new capital

The new capital rules will be phased in over several years, and will only be fully operational by 1 January 2019.

Controversially, the capital conservation buffer will only apply after 2016.

That implies there will be no restrictions on banks' ability to pay dividends and bonuses for over three years, even though many banks have far too little capital.

Special allowance has been made for banks rescued during the financial crisis - they will have 10 years to fully comply.

Governments have given their banks so much time because they are afraid that if the change is rushed, then the banks are more likely to cut their lending, pushing the world back into recession.

So is it the same rules for everyone?

Not quite.

The rules set a minimum standard, but some countries may choose to set stricter standards.

And it will also be up to individual countries when to apply the counter-cyclical buffer.

There are also higher requirements still to come for the biggest banks, whose failure could bring down the entire financial system.