Janet Street-Porter: If only I were Prince Charles...

He needs to bite the bullet and pay his taxes just like me if he considers himself fit to be king

Recently, however, I was advised by experts that, given my years, it was about time I wrote a will. This is not necessarily a depressing experience until you come to the part about inheritance tax. Having no children, pets, parents or secret lovers to provide for, my main concern was to make sure that my long-suffering partner could remain living in our house.

I was told, that if we were a homosexual couple who had taken advantage of the change in our laws to enter a legally binding union, all would be hunky dory. But as we are not, I either have to enter into another marriage (and with my track record standing at four failures, that's not exactly a promising scenario) or pay hundreds of thousands of pounds of inheritance tax on my death, possibly forcing my partner out of our home.

At this point I threw my hands up in despair. I've worked since the age of 21, and paid all relevant taxes, from Paye to corporation tax, without complaint. My big problem is that I'm not Prince Charles; I just have normal, common blood running through my veins, not the other kind that renders you immune to all sorts of rules, regulations and taxes. At this point I felt like picking up the phone and begging the Prince's private secretary, Sir Michael Peat, to pop round and offer me some advice in creative accounting.

Today, the influential House of Commons Public Accounts Committee will publish its report into the finances of the Duchy of Cornwall. Leaks in the media indicate that its members, of all political persuasions, are going to be highly critical of how Prince Charles runs the Duchy, first set up in 1337 to provide an income for the heir to the throne. Consisting of huge tracts of land in Somerset, Devon, Cornwall and most of the Scilly Isles, the estate is currently valued between £470m and £505m. Charles's personal income from the estate has grown tremendously, to £13.2m in his last published annual review, from £9.9m in 2003, almost doubling over the last five years. Controversially, though Charles may have elected to pay income tax at 40 per cent, he is exempt from capital gains tax, corporation tax and inheritance tax. Jammy or what?

Before Sir Michael starts putting pen to paper to attack me as an anti-monarchist, I most certainly am not. Interestingly, Prince Charles and Camilla recently dined with Gordon Brown and his wife, and Mr Brown is said to be furious with the Parliamentary Accounts Committee, which wants to put Charles's finances under the scrutiny of the National Audit Office. As Mr Brown senses the Big Job waiting for him just a few steps down the road, he doesn't want to start his relationship with the Prince on the wrong foot.

But it's not a sign that you would like to see Camilla working in Boots or Charles packed off to run a wind farm if you simply ask that the heir to the throne pays the same taxes as everyone else in his position, and runs his business in a transparent way, just as we ask of the BBC and other public bodies.

Sure, Charles receives no income from the Civil List, but by chairing the committee which decides how to apportion the balance between capital and revenue for the Duchy of Cornwall, he is in effect setting his own salary (and raising it annually) - a clear conflict of interest.

Then there is the Prince's charitable work, which raised £109m for good causes, using £2.5m of his own money to fund salaries and so on. Be clear - the Trust raised the money, not the Prince himself. According to Sir Michael Peat, Charles is "the greatest charitable entrepreneur in the world". So we can forget about Bill Gates, Elton John, Lily Safra and all the others who use their own considerable wealth to fund charitable foundations fighting Aids, feeding the needy and helping to give children clean water all over the world. What about all the millions in donations given by ordinary people which represent a far higher slice of their annual income?

When we delve into the review of the Prince's finances published earlier this month, complete with page after page of our heir in all his many guises, it becomes clear that the Prince receives a hefty rent from the use of his property for seminars and charitable causes. In addition, he pocketed £336,000 from the use of Highgrove, paid into his personal account, and has received the grand total of £8m in this way since he bought the estate in 1980. All this is what any smart accountant would tell you to do - it just rankles when the person benefiting wears his charitable work so proudly on his sleeve. I might have raised over £90,000 for charity appearing on a TV show last year, but I can tell you, the taxman wouldn't let me claim one frock, one tube of lipstick, and one hairdo as a business expense. At the end of the year, my company pays corporation tax.

Gordon Brown is just being plain inconsistent if he allows Charles to continue to run the Duchy as a private fiefdom. Charles claims over £2.6m from taxpayers for his official travel, communications and property maintenance; in return, we can expert that his accounts are subject to the same scrutiny as any other medium-sized business.

As the Duchy moves to invest in commercial property, its profits are bound to increase. And when there is a blurring between private and public expenditure - the use of private homes for business meetings, the use of private staff to service charitable functions, then it is right that accounts should be properly audited and filed at Companies House.

Charles now receives a larger income from the Duchy than the Queen does from the Civil List. His personal expenditure has continued to rise - and currently stands at around £5m. But I'm not going to beef about that - there are plenty of rich businessmen and pop stars who do the same. And if he wants to have nearly 30 personal staff of the Duchy's total of 93, including four chefs and several valets and butlers, I'm not complaining.

But using your success as a fund-raiser for good causes should not exempt you from complying with standard business practice in the UK. Prince Charles would like to operate as if he were the ruler of a banana republic or resident in a tax haven in the tropics. Sadly, those days are over, and Gordon Brown should be encouraging the heir to the throne to fall into line with his subjects and UK tax law.

Taking Camilla around the country in fancy hats and proudly displaying her to your subjects is going to win some brownie points, but no more. The Prince needs to bite the bullet and pay corporation tax, inheritance tax and capital gains tax just like me if he considers himself fit to be king.