Inheritance Tax: definition of 'normal expenditure out of income'

My elderly mothers regular income (i.e. pension & interest income) currently exceeds all her usual costs (all her regular bills, entertainment & holidays etc.). This has been the case for (at least) the last 5 years. However, in the past couple of years her house she has required some one-off costs / expenditure items (e.g., installed a new boiler and fixed some drain problems etc.). And may require some similar costs in the future. From an Inheritance Tax perspective, should these ‘one-off costs’ be excluded or included when calculating the outgoings for the ‘normal expenditure out of income’ rule? Thank you.

Hi,
Please contact the Inheritance Tax team for advice.
Inheritance Tax: general enquiries
Thank you.