There may be four months to go until the new tax year, but accountants are urging people to act now over changes that will introduce 50% income tax, raise the minimum retirement age and scrap tax relief on holiday lets.

From April 6, those earning £150,000 or more will be taxed at a maximum rate of 50%. David Kilshaw at KPMG, the accountant, said: “By being smart about the timing of financial decisions and ensuring that they take full advantage of tax allowances, people can, to some extent, mitigate the effects of the new top rate.”

Meanwhile, the minimum retirement age will rise from 50 to 55 on April 6. People in their early fifties — those born between April 7, 1955 and April 5, 1960 — who want to take pension benefits will have to do so within the next four months, or wait up to another five years.

If you have a UK holiday let, you also have only a few months left to claim tax relief on expenses relating to the property. Here, we give our top 10 tips:

1 SAVINGS AND BONDS

If your deposit accounts pay interest only once a year and that falls after April 5, think about closing the account so that interest accrued to date will be taxed in the current tax year.

Consider cashing in investment bonds and gilts (government bonds). Higher-rate taxpayers can take 5% a year from investment bonds with no tax to pay but it becomes due at your highest rate when the bond is cashed in, so it’s wise to do so while in a lower band.

The growth in value of gilts is subject to income tax, too.

2 TRANSFER ASSETS

If you earn more than £150,000 and your spouse doesn’t, transfer income-producing assets.

Say you had a portfolio of investment properties worth £500,000, which produced an income of 5% or £25,000 a year. If you were a high earner and held the investments in your own name, you would be liable for tax of £12,500 from 2010-11.

If you gifted these to a spouse who doesn’t work, the first £6,475 would be tax-free and the rest taxed at 20% — so just £3,705, said Saffery Champness, the accountant.

3 BRING FORWARD INCOME

Shareholders in their own businesses who take money as dividends will be taxed at 32.5% until April 5, rising to 42.5% the following day.

On £10,000-worth of dividends, you would save £1,000 in tax by bringing the payment forward. Bear in mind, though, that you would also have to pay the tax via your self-assessment form a year earlier.

4 SHARE INCENTIVE SCHEMES

High earners could ask their employer to set up a share incentive scheme ahead of the changes so, instead of taking cash bonuses, they could receive shares in the firm. This converts income taxed at up to 40% today (or 50% from April 6) into gains taxed at the flat rate of capital gains tax (CGT) of 18%.

Share options worth £10,000 would be liable to income tax when exercised, but if the shares had risen in value to £50,000 when sold, there would be a CGT charge of £7,200 on the £40,000 gain. Had you received a bonus of £50,000, you would pay income tax at 50% — £25,000 (£17,800 more), said Saffery Champness. There is no guarantee the shares will appreciate and if you try to eliminate this risk, you will fall foul of tax rules.

5 DEFER TAX RELIEF

Consider deferring claims for tax relief until the 2009-10 tax year has ended on April 5, boosting potential tax relief to 50% from 40%. Say your business bought a piece of machinery for £40,000 in this tax year and you are a 40% taxpayer, you could claim tax relief of £16,000, but if you delayed the purchase, the relief would be worth £20,000.

6 REVIEW FAMILY TRUSTS

It could be worth drawing income arising in a family trust. This is taxed at 20% on up to £1,000 and 40% thereafter, rising to 50% from April.

Ronnie Ludwig at Saffery Champness said: “Even trusts with a small amount of income will be hit with 50% tax.”

Alternatively, beneficiaries could draw the income if their other earnings are below £150,000.

7 CRYSTALLISE PENSION BENEFITS

People in their early fifties who want to retire early, or unlock tax-free cash from their pensions, should consider doing so before April 5, when the minimum retirement age goes up from 50 to 55.

However, advisers said there are some instances where it is not advisable to take the cash. For example, if your pension has a guaranteed annuity rate (say, over 9%) you would be better off using your entire fund to buy an annuity.

Those in final-salary schemes who can choose to take extra tax-free cash and a reduced pension should also take care, as the income you would give up is guaranteed, inflation-proof and has a widow’s or widower’s benefit. However, in other cases it could be worth crystallising benefits. Danny Cox at Hargreaves Lansdown, the adviser, said: “Repaying debt is almost certainly the best investment you will make. If the interest on a loan is at 6%, your investments need to achieve 10% as a higher-rate taxpayer just to keep up.”

Equally, it may be worthwhile if you want to free up cash to make gifts for inheritance tax planning or make other tax-efficient investments.

8 RETIRE FAST

Advisers fear people could be caught out by delays in processing payments before April 6. Tom McPhail at Hargreaves Lansdown said: “Don’t leave it until the new year — do it now.”

Ian Hammond, managing director of Rowanmoor Pensions, said: “To complicate this issue further, the last working day of the tax year is Thursday April 1, 2010, due to bank holidays, so anyone whose 50th birthday falls between April 1 and 6 can’t possibly comply with the legislation.”

9 MAKE CONTRIBUTIONS NOW

Hargreaves Lansdown is writing to 110,000 clients urging them to make pension contributions before the pre-budget report on December 9. The government already plans to claw back tax relief on contributions for those earning £150,000 and the adviser fears it could extend this to £100,000.

10 REVIEW HOLIDAY LETS

If you let property short-term, this is the final tax year in which you can offset expenses against income, so get any work done on the property before April 6. It must be let for at least 70 days a year, excluding lets exceeding 31 days, and be available for rental for at least 140 days, said Smith & Williamson, the adviser.