Letting expenses

...which had been let in the past but was subsequently vacated. This was transferred to his wife in April 1999 at which point it was empty to form part of her 'letting business' but was never subsequently let before it was sold in July 2000. During the period of her ownership there were various expenses incurred and she wonders if she is able to offset these against the income from the other let properties.
Given that all let properties are treated as if they were one business is this offset possible?
In the past the other let properties have shown a deficit due to the level of mortgage interest and other expenses and it is probable that this will also be the situation for 1999-2000 and 2000-01. It is hoped that at some point in the future a surplus will...