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HMRC internal manual

Inheritance Tax Manual

Valuing the partnership interest: Other assets

The figures for stock, plant and machinery, debtors, cash at bank and other miscellaneous items can often be accepted without query. If they appear to be less than the expected open market value you will need to decide if the tax at stake justifies investigating this value.

If you decide to investigate the values and the balance sheet refers to a valuation, you should ask for a copy.