IHTM23132 | Other communications received from the VOA: taxpayer's figure is unacceptable
From HM Revenue & Customs · Inheritance Tax Manual
If the VOA (IHTM23002) is unable to accept the taxpayer’sfigures, they will notify the taxpayer of the revised valuation on form VO 1001.
If there is no response from the taxpayer within 4 weeks the VOA will
send a reminder on form VO 1002, and
hold the papers a further 2 weeks
At the end of that period the VOA will send an interim report (IHTM23081),or seek assistance, as appropriate.