A messy workbook: the order to diagnose it in, and where each fix leads

1. Is it recalculating?

Check the calculation mode before anything else. A workbook set to recalculate only on request shows old results, and every other check is meaningless on stale numbers. Force a full recalculation and see whether any figure moves. The guide on wrong totals without error messages explains manual calculation, numbers stored as text and displayed versus stored values.

• Next: if figures move, you have found one cause; recheck everything after recalculating.

2. Which errors show, and which are hidden?

List the error values by type: #REF!, #NAME?, #VALUE!. Each points to a different break. Then look for silent damage: values typed over formulas and ranges that stop short. The error-values guide shows how to trace a formula to its inputs and why hiding an error is not repairing it. If the workbook's outputs cannot be trusted, the fixed formula repair, from £195 for one workbook, is accepted by check cases you work out independently.

3. Is the layout a table?

Merged cells, spacer rows, repeated headings and subtotal rows must be flattened before sorting, filtering or a PivotTable. Do this once the workbook is recalculating and its formulas are sound, but before you test numbers and dates: a print layout puts subtotal and heading text inside the number and date columns, so those columns cannot be typed correctly until the data is a flat table. The merged-cells guide and the worked example show the reconciliation. The flattening job is from £145 for one sheet.

4. Are the numbers real numbers?

Numbers stored as text align left and are skipped or mis-sorted. Codes that need leading zeros must be text from the start. This is checked once the layout is flat, so that heading and subtotal text is not mistaken for bad numbers, and before dates and duplicates, because both depend on values being the type you think they are.

5. Are the dates real, and unambiguous?

Dates can be text, shifted by 1,462 days between Excel's two date systems, or typed day-first and month-first in the same column. The dates guide and the worked ambiguity example show which rows a written rule can settle and which must stay on a list. The clean-up job, from £125 for one file, handles steps 4 and 5 together and never guesses.

6. Are there duplicates, and by what rule?

Deduplication comes after dates and layout, because duplicates cannot be reliably matched while the fields are still inconsistent. Write the match rules first, keep a merge log and treat uncertain pairs as review items. The duplicates guide explains why Excel's Remove Duplicates compares displayed values and deletes permanently. A list of products, parts, assets or companies with no personal data can be de-duplicated as a job from £195; lists of people are not covered.

7. Is it ready for the next system?

Last, check readiness: one header row, one type per column, blanks decided, keys unique and a column list that matches the target. The readiness guide sets out the sheet. If you have several workbooks with several kinds of damage, a project from £1,500 runs these steps in order across the set. Prices are untested proposals; payment follows agreed checks and your sign-off. Files are handed over only by a secure route agreed in writing first, and no upload portal exists yet. Nothing here loads data into a live system, and nothing is accounting advice.