As homeowners gradually move up the property ladder they might start to consider whether their new des res will make them a profit or will be able to accommodate any new additions to the family.

The taxman rarely figures in these thoughts. But if your estate is worth more than the inheritance tax threshold of £285,000, he will be entitled to a 40 per cent slice of the excess.

And one in ten homes across the Midlands are now worth more than the threshold figure, which could mean a nasty surprise for loved ones destined to inherit the family home.

Among the many homeowners waking up to this realisation are PR professional Jeremy Merckel and his wife Andy, a business development manager for a city law firm.

The couple own a four-bedroom terraced property in the up and coming area of Wylde Green, Sutton Coldfield, currently worth £290,000.

They have also saved a substantial amount and are about to undertake extensive building work which is sure to take the value of the property substantially over £300,000.

But all their efforts at work and on extending their home could be costing them more than they imagined.

When the couple bought their home in May 2005 for £238,500, they did not anticipate being caught in the net of another tax, especially not inheritance tax.

Mr Merckel, aged 32, said: "While we are thrilled to have made such a sound investment, we didn't realise that inheritance tax would be something that we would have to worry about. We're just a typical, middle class couple, not the landed gentry.

"I think that a lot of people in our situation will be completely oblivious to the fact that their estates will be liable for inheritance tax, which is quite worrying.

"Although we don't have children now, we certainly plan to in the future and want to protect our investments for them."

Tracey Macintosh, of accountancy firm BDO Stoy Hayward, said: "In Jeremy and Andy's case, this tax burden would rest with their children, who could be forced to sell the family home to pay the outstanding inheritance tax threshold sum.

"Fortunately, there are alternatives. The best thing that Jeremy and Andy could do is ensure that they have tax efficient wills in place. This involves leaving part of the estate to a discretionary trust when the first spouse dies.

"We strongly recommend that homeowners in the Midlands who suspect they may now fall into this category arrange to have their home valued."