Hi Steve,
this is a difficult question given the data required is coming from a number of different stakeholders and departments within any organisation. The obvious answer is to have a strong relationship with all of the stakeholders and ensure they understand the consequence of changing or adding new data with what they provide through to your TBMA office (as @Paul Melican has suggested). Unfortunately staff turnover and organisational restructuring will make this a challenge.
In Apptio, we provide Managed Services to those businesses that do not have the current capabilities of maintaining an internal TBMA office. Data validation is part of this solution, and is managed in a couple of ways:
1. having a spreadsheet of all data sources and information about them (eg. how often they are uploaded, by what date, how is the data owner, what is the data source system, number of columns, rows, etc). This makes it easy to check and keep on top of your data required for month end processes.
2. a "data validation" mechanism, that allows you to review new data sets and compare with previous ones. The focus here is not so much on the individual values in your data set, but the format (ie. columns headers match, row counts look comparable, types of data in each column, etc). While this wont highlight if a new cost centre has been introduced, it will show you if data has changed from the source system.
3. review reports, the data quality reports are an excellent resource to highlight issues within your model (particularly the Summary report). When comparing against previous months, check what values have changed. This will help you understand where your model is different and if the underlying data is the driving force.
I hope you have found a few skills here and from the previous responses to make SEQ successful.
Regards Mark