We've done a lot of giving to charity as a nation in the past few weeks. First was the Christchurch earthquake, which impelled many to give way more to charities than they usually would.

Then came the Japanese earthquake and tsunami, which sent people reaching for their wallets again.

Many national charities not directly involved in either catastrophe are worrying that giving, as a result, might be down for them.

Charities such as Kidney Kids, which is raising money to build a dialysis unit, are hoping their incomes will not be affected.

Kidney Kids chief executive Paul Norfolk says his charity's Perspex collection boxes have been moved aside in many places to make way for Christchurch appeal boxes.

"We don't mind with a situation like this," he says.

The pressure is on, however, to maximise income from other sources such as sweet selling, clothing-bin donations and hotels that encourage customers to donate to Kidney Kids.

Many charities have been affected. Plunket, for example, delayed its March appeal and others with February appeals are expecting takes to be down.

That charities' incomes might suffer this year is just anecdotal at the moment, says Robyn Scott, chief executive of Philanthropy New Zealand.

Scott hopes - as does the entire charitable sector - that the giving to Christchurch is new money, not repurposing of existing giving by the public or corporates, neither of which have bottomless pockets.

Her fear in particular is that the corporates that have donated large sums to Christchurch appeals will deduct it from corporate responsibility accounts - rather than it being added to existing budgets.

No one will know exactly what has happened until the quarterly generosity indicators are released by the Office for the Community and Voluntary Sector.

If history repeats itself, we will return to giving to our usual charities once the urgency of the Christchurch and Japanese earthquakes passes, says Trevor Garrett, chief executive of the Charities Commission. After an emergency such as Christchurch, there is an emotional pull to try to support victims.

"Then over a period of time you perhaps move back to your normal way of doing things," he says.

We give a lot to charity as a nation, but New Zealand has one charity for every 172 people. That means an awful lot of giving to keep so many charities afloat.

It's not unusual for charities to spend more than 15 per cent of donations on operational costs.

On the positive side, Kiwis are first-equal with Australia in the World Giving Index, according to the International Charities Aid Foundation, which released its index last year.

That doesn't mean we all dig into our pockets to give. Some people give beyond their means. Others barely give anything.

Charities always struggle to raise money, earthquake or no earthquake, and rely on you and me to be generous.

Some people feel 10ft tall and bulletproof - thinking they'll never need charity. Yet, anyone of us could be struck down with a heart attack, cancer, dementia, kidney failure and much more.

Whatever the affliction, charities are working to find cures and assist sufferers for almost every illness known to man - which could benefit them or a family member in the future.

Be it Christchurch or any of the other good causes around, putting thought into how you give can make it more cost effective.

Donations to registered charities are tax deductible. That means provided you give to the right cause and get a correct receipt, you can claim back the tax you paid on that money. Or, if you prefer, you can give more to the charity of your choice.

Even better, say charities, sign up for payroll giving. This way a regular amount is taken from each pay packet. From the charities' perspective it's an intravenous line into your wallet.

Small payments add up to a lot over your lifetime. It also means the charities can forge a relationship with you, and hopefully encourage you to make larger donations when finances permit, or to leave a bequest in your will.

Although bequests are an important source of income for charities, they would rather have your money during your lifetime than after death.

What's more, donations given to registered charities during your lifetime come from gross income, whereas money donated through a will is from tax-paid income.

There are advantages to payroll giving from a donor's point of view.

Payroll giving generates an automatic tax refund, which means you get the tax back immediately or can add it to your donation. With other giving you would have to wait until the end of the tax year to fill in an IR526 and claim a refund.

Another bonus for individuals looking for tax refunds from their charitable giving is that the thresholds were increased in recent years.

Since March 2009 it has been possible to reclaim one-third of the total donations you have made in a year - providing that doesn't exceed a third of your taxable income.

Tax isn't the be all and end all of giving. There are many little ways to make a difference.

For example, when someone marries, or dies, if you don't want a gift or flowers, ask for a donation to be sent to your favourite charity.

You can also give goods to charities. Smaller charities, in particular, are often grateful for everything from office supplies to goods that can be used to benefit their causes.

Plenty of individuals were willing to give goods in the immediate aftermath of the Christchurch earthquake. Some are still baking for Christchurch, says Scott. Such donations of goods aren't tax-deductible.

It's not just Christchurch. People give goods regularly on a small scale - for example, donating useful items to local charities or simply depositing food in the SPCA and City Mission bins at supermarket checkouts.

There has been in-kind giving for the Christchurch earthquake, says Scott, whose husband is about to spend a fortnight in the stricken city as a volunteer plumber.

That gift of time is very useful to charities, which need volunteers, says Garrett. "Charities want people's time in all sorts of different ways. Sometimes it is just manning a booth or doing the cleaning. Sometimes it is in governance."

Kiwis aren't quite as good at giving up our time as our money, according to the World Giving Index. Asked if they had volunteered time for an organisation in the last month, 41 per cent of Kiwis said they had. We were beaten on that count by nationals of Sri Lanka and three African nations.

Organising fundraisers is a very good way to support charities.

Thousands of such fundraisers have been held for Christchurch in recent weeks, with many still planned. Sometimes it's a matter of passing a hat around at work.

Fundraisers also come in high-tech forms, and can be remarkably successful. For example, Vic and Joy Hayes, members of the Mini Car Club of Auckland, had earlier this week received pledges of $15,030 at www.fundraiseonline.co.nz/JoyandVicHayes/ to complete the annual Pork Pie Run, which raises money for the Starship Foundation.

Receiving pledges online is a lot easier than shoulder-tapping friends, colleagues and family or going door to door. Websites such as FundraiseOnline ensure your $10 donation is automatically tax receipted, meaning the individual donor can claim their take back.

The downside for some donors is that their contact details are passed on to the charities. Not everyone wants to be plagued by phone calls, emails and letters from charities if they've only given once.

Garrett warns individual donors against scams and says always ask for a charity's registration number before giving money. It's all too easy for someone to wander down to a shopping centre with a "collection bucket" and keep the money for themselves.

Even more worrying are online scams that purport to be raising money for charity but are simply hoaxes in order to part generous people and their cash.