My kid brother turned 50 last month, a milestone which provided the perfect excuse for a family knees-up.

Rarely have I enjoyed one more though, even now, I fail to appreciate the detrimental effect drinking neat Scotch at 3am can have upon one’s constitution.

Fifty, I’m reliably informed, is the new 30 and though I hardly felt like a 30 year-old on the Sunday morning after my brother’s birthday, it’s comforting to know that from last month, those of us who have managed to hit the fifth decade mark have been handed an investment advantage not yet available to younger folk.

Provided you turn 50 before April 6, 2010, you are entitled to shelter an extra £3,000 in an individual savings account (ISA), bringing the annual allowance to £10,200.

This may either be fully invested in a stocks and shares ISA or split equally with cash.

It’s taken a while for the benefit of ISAs to be fully appreciated, but even when compared with some of the generous tax breaks offered by pensions, those available to ISA holders are worth having.

For example, people nearing retirement who are investing for income would be well advised to consider maximising their ISA investments.

This is because income generated from a pension is taxable, whereas that produced by an ISA is just about tax-free.

The exception is if you hold dividend-yielding shares within your ISA, the dividend is taxed at ten per cent and cannot be reclaimed, although income generated from an equity income fund is tax free provided the fund is held within an ISA.

Furthermore, interest earned from corporate bond funds is also generously treated if they are held within an ISA as the ISA manager can claim a 20 per cent tax credit on the income received. As equity investors know, the ability to claim a tax credit on share dividends disappeared long ago.

Nevertheless, 50-somethings have been handed a rare opportunity and there is good reason to consider investing in the autumn, rather than wait until next April when unit trust and investment trust prices tend to rise.

According to research published by fund manager Fidelity International, investing your full ISA allowance in October instead of in the spring would have netted an extra £7,500 over the past 15 years, assuming your investment had performed in line with the FTSE All-Share index.

The reason for this is simple — investing earlier in the tax year rather than towards the end gives your money more time to grow.

But ISAs enjoy one often overlooked pension-related benefit.

Most of us invest for our retirement, though whether every penny should go into a pension is debatable.

This is not as controversial as it may sound, because should your pension income breach the annual allowance (for people over 65 it’s currently £9,490), you become liable for tax.

It is possible, therefore, to stay below this threshold by investing a proportion of your money into an ISA, the income from which is tax-free.

After our heads had cleared, I explained this to my brother last month.

“Can we talk about this another time?” he moaned. “Let’s have another drink.”

We did, but I still urged him to get cracking and utilise his ISA allowance now he’s in the crinkly zone like his (slightly) older brother.