The settlement, involving art works and furniture worth as much as pounds 10m, would be the largest Acceptance in Lieu arrangement ever made.
Eight years after he inherited the Palladian Houghton Hall in Norfolk on the death of his father, Lord Cholmondeley, 37, and the Inland Revenue look set to confirm a deal by the summer.
The estate was valued at pounds 118m, with artworks thought to account for the bulk of the sum.
Under an arrangement being negotiated with the taxman, major items of furniture may pass to the Victoria and Albert Museum in London.
Until now, the largest such arrangement has been for four paintings valued at pounds 6.6m accepted in lieu of tax from Eva Borthwick-Norton in 1990.
A spokeswoman said Lord Cholmondeley did not want to comment in advance of the "satisfactory conclusion" of negotiations with the Department of Culture.
"It is usual in such cases for the minister to announce the conclusion of any deal and it would be inappropriate to pre-empt this in any way," she said.
The Museums and Galleries Commission, which advises the ministry, is understood to have valued the artworks proposed for acceptance by Christmas 1996. Since then, the department has been examining their recommendations. A spokesman said an announcement was now likely "in the next month or so".
Since his inheritance, Lord Cholmondeley has caused some upset by selling off parts of the Houghton Hall estate. A painting by Holbein, Lady with a Squirrel, was bought by the National Gallery for pounds 10m in 1992 and in 1994 he sold off French porcelain, furniture and paintings in a pounds 21m sale at Christie's.
It was argued in defence that many of the items had been in storage for a long time and a majority were amassed by the marquess's great uncle, Sir Philip Sassoon, who died in 1939.
A spokeswoman said that his intention has always been to preserve the original contents of Houghton: this includes family pictures and paintings from the collection of Sir Robert Walpole, Britain's first prime minister.
"The rest of the collection has changed considerably over the years as successive generations have bought and sold works of arts," she said.
"As well as making judicious sales, Lord Cholmondeley has added considerably to the collections and hopes to continue this policy in the future."
The marquess, whose other family home is Cholmondeley Castle in Cheshire, holds the ancient office of Lord Great Chamberlain. One of his duties is to walk backwards as he leads the Queen to the State Opening of Parliament.
Lord Cholmondeley is known in the gossip columns, where he has appeared dating the model Lisa B and escorting beauties including Isabelle Adjani.Reuse content