Inheritance tax planning errors could cost families hundreds of thousands of pounds, an expert has warned. Laura Rumsey from Rogers & Norton Solicitors said she regularly sees families caught out by "avoidable" IHT mistakes. She said: "These are not complex loopholes - they are straightforward steps that many people just don't realise they need to take. By understanding the rules and planning ahead, families can protect what they've worked hard for and avoid leaving their loved ones with an unexpected and potentially devastating bill."

Laura said couples may not realise the financial consequences of not getting married. She explained that you can claim spousal exemption if you are married and leave assets to your spouse. The expert added: "This is important as the transfer between spouses on death means none of the estate is lost to tax."

She said this allows assets to be passed on tax-free, with their unused tax-bands also available when the second spouse passes away. Laura said this potentially means families can pass on up to £1million free of inheritance tax.

Laura said: "Being married really is beneficial for tax planning and remember that legally there is no such thing as a common law spouse."

The expert said an unmarried partner inheriting an estate worth £500,000 could face a bill of around £70,000. Laura described this as a costly shock many simply don't see coming.

Another loophole families can forget relates to property. Passing on the family home can unlock a tax-free allowance, according to Rogers & Norton.

Laura said: "If you have a property you are planning to leave to your children, you can claim up to an additional £175,000 each - for you and your spouse - depending on the value of your property."

Combined with standard nil rate bands, this could mean if a married couple has children they may be able to claim up to £1m in tax-free allowances on the death of the second spouse.

Rogers & Norton said families risk losing part of the allowance and possibly paying more tax without planning properly beforehand.

A third error identified by the expert applies to a two-year rule which could save families hundreds of thousands. Laura explained: "Often people's wealth can be generational and to avoid double taxation of the same assets it is possible to consider deeds of variation.

"These legal documents allow adult beneficiaries with capacity to change the distribution of their inheritance to other people usually their children for example. This means the gift comes from the original deceased and can, for example, bypass a generation, ensuring wealth is passed on efficiently."

She said those deeds of variation can be prepared up to two years after the date of death, which according to Laura allows for careful planning prior to acting.

Laura concluded that for families willing to take advice, the two-year window could make a "substantial" financial difference.