The client sent you their spreadsheet. How do you check it before your name goes on the numbers?

Guide · Updated September 2026 · ~22 min read

The client's own workbook arrives on a Tuesday. Six tabs, two of them hidden, a Summary sheet whose gross margin looks about right, and an email saying this is what they have been running the business on for three years. You have to produce a set of accounts off the back of it.

Reading the numbers tells you nothing. A total typed in as 184,300 looks exactly like a total that calculates. A =SUM(B8:B10) sitting under eleven rows of data looks exactly like one that reaches the bottom. A figure fed by a link to a file on somebody's old laptop looks exactly like a figure that is not. A workbook left in manual calculation mode shows you last month's totals with this month's inputs above them, and looks completely normal. Every one of those is something you would be putting your name to.

This is the twenty-minute review: nine checks that surface the plugs, the short ranges, the external dependencies and the stale overrides, ordered so the worst finding turns up first. After that, the three findings that mean rebuild rather than repair — and the four clean workbooks we maintain, as direct .xlsx downloads with their limits stated, for when rebuilding is the answer.

What you are actually being asked to do

There is a line between using a workbook and standing behind it, and the client who emails you a spreadsheet has usually not noticed it exists. They are handing you a tool. You are being asked to turn its output into something with your name on it.

So be clear what the procedure below is and is not. It is a review to decide whether you can rely on a file. It is not an audit in any professional-standards sense, it applies no framework, it samples nothing, and it produces no opinion — a workbook that passes all nine checks can still be comprehensively wrong about the business, because every formula in it can be correct and every input fabricated. What these checks find is the class of defect that is invisible on screen and fatal to anything built on top: a number that does not calculate, a range that does not reach, a dependency that does not resolve.

What a finding obliges you to do is narrower than it sounds, and there are only two answers. Either you go back to source — the bank statements, the sales ledger, the invoices — and derive the figure yourself, or you rebuild the part of the workbook that produced it. What you must not do is repair the symptom: overtype the plug with a better plug, or widen the SUM range and carry on as though the three months it previously missed never happened.

The twenty-minute review, in order

Nine checks, ordered so that the findings which invalidate everything downstream come first. If check 2 fails, none of the numbers you have looked at so far mean anything, so it is worth doing them in sequence rather than dipping in.

1. What kind of file is this?

.xlsx cannot hold a macro; .xlsm can. If a workbook arrives macro-enabled and you were not expecting it, ask why before enabling anything — a client's three-year-old trading spreadsheet has no obvious reason to contain code, and "it has always done that" is not an answer to the question of what the code does. This is first on the list because it is the only check you make before opening the file rather than inside it.

If you do enable it, look at what you enabled: Alt+F11 opens the editor and the project tree shows every module. A workbook whose macro turns out to be a recorded print routine is fine. One that writes values over formulas on open is a different conversation.

2. Is it actually calculating?

Formulas > Calculation Options. If it reads Manual, stop and read nothing else until you have pressed F9, because every total on screen was produced by a set of inputs that may no longer be there. This is the most dangerous finding on the list and the least visible: a workbook on manual looks completely normal, the formulas are all present and correct, and the answers are simply from a previous era.

Two things to know. The calculation mode is saved in the file, so the client's habit travels to you. And Excel applies the mode of the first workbook opened in a session to the whole session — so an inherited file on Manual, opened first thing, quietly puts your own workbooks on manual too. Press F9, watch what moves, and if anything material changed, that is a finding in its own right: whoever was using this file was reading stale figures.

3. Show the formulas

Formulas tab > Formula Auditing > Show Formulas, or Ctrl+`. Every total should be a formula; anything typed as a constant where you expected a calculation is a plug. This one view, on each sheet in turn, is the fastest thirty seconds in the whole review — you are not reading the formulas, you are scanning for the cells that do not have one.

4. Find the plugs

F5 > Special > Constants > Numbers highlights every typed number at once. Inside a block of inputs that is meaningless — inputs are supposed to be typed. Inside a calculating block, that is your list of things to question, and it is the list to take back to the client one item at a time: where does this figure come from?

Expect an argument about the small ones. Hold the line on any plug that sits inside a total, because a hardcoded number in a calculating block does not update when anything else does, and nobody will ever remember it is there.

5. Do the SUM ranges reach the bottom?

Click each subtotal and read its range against the block above it. A =SUM(B8:B10) sitting under eleven rows of data is the commonest template defect there is — and in a client's own workbook it is commoner still, because rows get added at the bottom of a block for years and the total never follows. Selecting the cell puts a coloured border round the range it actually covers, which makes a short range obvious without reading a single reference.

The version of this that catches people out is the row inserted directly above a subtotal. Excel usually extends the range; it does not always, and the failure is silent.

6. Trace one number end to end

Select a headline total — gross profit, net assets, whatever the client quotes at you — then Formulas > Trace Precedents, and follow it back to an input. If the trail leaves the workbook to a file you do not have, stop.

A dashed arrow ending in a small worksheet icon is Trace Precedents telling you the precedent is in another workbook. To see what that file is, Data > Edit Links lists every external source and its status — recent Microsoft 365 builds put a Workbook Links pane in the same place instead of the dialog. A source reporting an error, or pointing at a path on a machine nobody still has, means the figure downstream of it is frozen at whatever it was the last time the link resolved.

7. What is hidden?

Right-click any sheet tab and choose Unhide to see the hidden sheets. Then note the trap: a sheet set to very hidden does not appear in that list at all. It is not a security feature and it is usually not sinister — it is how somebody tidied away a working tab years ago — but a calculation living on a sheet you cannot see is a calculation you have not reviewed.

To find them, Alt+F11 for the VBA editor, then look at the project tree: every sheet in the workbook is listed there whatever its visibility, and the Properties window shows the Visible setting for the one you select. Hidden rows and columns deserve a glance too — a hidden column inside a summed range contributes to the total in complete silence.

8. Open the Name Manager

Formulas > Name Manager (Ctrl+F3). You are looking for two things. Names whose Refers to shows #REF!, which means the range they pointed at was deleted and every formula using that name is now broken — and a broken name propagates its error into every total downstream. And names that point at another workbook, which is the same external-dependency problem as check 6 wearing a different hat and much harder to spot, because a formula reading =Turnover gives no hint that Turnover lives in somebody else's file.

A long list of names created by pasting from other workbooks is not itself a defect. A list with errors in it is.

9. Are the numbers numbers?

A column of figures that arrived from an export, a PDF or a web page is frequently text that looks like numbers, and text contributes nothing to a SUM. The total is not wrong in any way you can see; it is just smaller than it should be. Count them:

=SUMPRODUCT(--ISTEXT(D2:D5000))

Zero is the answer you want. Anything else tells you how many cells in that column are text, and cleaning messy data in Excel covers converting them back. Left-aligned figures in a column that is otherwise right-aligned are the visual tell, but do not rely on it — a client who has centred the column has removed your only clue.

The three findings that mean rebuild, not repair

Most of what the review turns up is fixable in place. Three findings are not, and recognising them early saves you a week of patching something you are going to replace anyway.

1. A plug inside a calculating block that the business has been relying on. Not a typed input — a typed result, sitting where a total should be, which nobody can now derive. Somebody put 184,300 in that cell in 2023 and every figure downstream has been built on it since. You cannot repair a number nobody can reproduce, and you cannot sign off a derivation that does not exist. Go back to source for that figure and rebuild the block around it.

What you say to the client: this total does not calculate from anything in the file, so I need the underlying records for it. Not "your spreadsheet is wrong" — it may well have been right on the day it was typed.

2. An external link you cannot resolve to a file you can open. A link to a workbook on a former bookkeeper's laptop is not a dependency, it is a dead end with a cached value in front of it. The number is frozen and nobody can tell you as at when. Chase the file once; if it does not appear, treat every figure downstream of that link as unsupported and rebuild those cells from source.

3. The same figure typed into more than one place. Turnover keyed onto the Summary tab, the VAT working and the year-end schedule. Today they agree, which is exactly why nobody sees a problem. But every future change now has to be made in three places by somebody who remembers all three, and one month that will not happen — and when it does not, the file will still look fine, because nothing in it compares the three to each other. This is the finding clients push back on hardest and the one most certain to bite. The replacement is one input cell and two references to it.

In all three cases the answer is the same: identify the smallest block you can honestly rebuild, rebuild that, and tie the result back to a record outside the workbook. Which is where a clean starting point earns its place.

The same six tests, applied to anything you download

A stranger's template off the internet is a workbook you did not build, so it gets exactly the treatment you have just given the client's. Before it carries a real number, six things separate a usable one from a thumbnail.

None of that proves a template is right for your entity. It does mean you know what it is doing, which is more than a thumbnail in a gallery ever tells you.

Four clean workbooks to replace it with

When the answer is rebuild, you need somewhere to rebuild into. These are the four workbooks we maintain — four direct .xlsx links, no email, no login, no "open in". All four are .xlsx, all four calculate, and each one names what it cannot do, which is the point: run the nine checks above on any of them and the only thing you will find is the limit already printed on the sheet.

1. Profit and loss statement

Download the P&L template — 2 sheets, no macros.

Two sheets: P&L and Transactions. The P&L runs a conventional five-block statement — revenue (rows 8-10), cost of sales (14-16), gross profit, operating expenses (23-30), net profit — with a period label in B4 and five columns: line item, this period, prior period, variance, variance %.

What calculates: B11 totals revenue with =SUM(B8:B10), B17 cost of sales, B19 gross profit as =B11-B17, B31 the eight overhead lines and B33 net profit as =B19-B31. Column D is the absolute variance (=B8-C8), column E the percentage change, guarded against a nil prior period:

=IFERROR((B8-C8)/C8,"")

The margin cells are B20 and B34, both =IFERROR(B19/B11,"") in shape — gross and net profit over revenue, updating as you type. One quirk before you label a printed pack: on the two profit rows (19 and 33) column E carries the margin, not the period-on-period change, so head it "Var % / margin" or blank those two cells for a board pack.

To use it: type this period's figures into column B, last period's into column C, and rename the eight expense lines in column A to your own chart of accounts. Add lines at the bottom of a block rather than inserting mid-block, then extend the SUM range above.

The Transactions sheet is the reason this beats a static form. Headers are Date, Description, Category, Amount, and F2 carries the pattern that wires the statement to a pasted ledger export:

=SUMIFS(Transactions!$D:$D, Transactions!$C:$C, "Marketing")

Paste your GL export there, then replace the typed figure in each expense cell with a SUMIFS pointing at its category, and the statement rebuilds itself every time you repaste. Two checks on a fresh export: amounts arriving as text (=SUMPRODUCT(--ISTEXT(D2:D5000)) should return 0) and category spellings that drifted — see cleaning messy data in Excel.

Limits: single entity, single currency, no consolidation, no budget column. Full walkthrough: building a P&L statement in Excel.

What the review above would find in it: typed constants in columns B and C, which are the inputs and are supposed to be typed; and, if you have replaced the expense cells with SUMIFS, a dependency on the Transactions sheet that Trace Precedents resolves inside the workbook. No plugs in a calculating block, no external links, no hidden sheets.

2. Balance sheet

Download the balance sheet template — 1 sheet, no macros.

One sheet, two comparative columns (this year / last year), an "As at" date in B4, and five blocks: current and non-current assets, current and non-current liabilities, equity.

The subtotals: B12 current assets, B18 non-current assets, B20 total assets as =B12+B18; B27 and B32 for liabilities with B34 as =B27+B32; B40 for equity. The row that earns the download is the check at the bottom:

B42:  =B20-B34-B40
B43:  =IF(ROUND(B42,2)=0,"OK - balanced","OUT BY "&TEXT(B42,"#,##0.00"))

So row 43 reads either OK - balanced or OUT BY 1,240.00, in both columns. The ROUND(...,2) is deliberate: figures carrying fractional pence would otherwise sit at 0.0000001 and report themselves broken forever.

The one trap: row 16 is Accumulated depreciation and it sits inside =SUM(B15:B17), so enter it as a negative. Type 48,000 instead of -48,000 and total assets overstate by 96,000 — which the check row reports exactly, though people have been known to plug that difference into retained earnings rather than read it.

To use it: enter this year in B, last year in C, and stop when row 43 says OK in both columns. If it does not, work the usual suspects — a sign, a line in the wrong block, B39 disagreeing with net profit on the P&L, or opening retained earnings never rolled forward.

Limits: no cash flow statement, no note disclosures, no roll-forward from the prior year. Structure, equation and what to do when it will not balance: balance sheet template in Excel.

What the review above would find in it: the same thing as the P&L — typed inputs, formula subtotals, nothing external. The one place it could go wrong in your hands is B39, the current-year profit cell, if you type net profit in rather than carrying it from the P&L. That is a plug you have created, and it is the reason the close-pack order below names the cell.

3. Bank reconciliation

Download the bank reconciliation template — 3 sheets, no macros.

Three sheets: Reconciliation, Bank statement, Ledger.

The Reconciliation sheet is the classic two-column proof. Bank side: closing balance per statement (B5), plus deposits in transit (B6), less outstanding cheques (B7), giving B8 = B5+B6-B7. Book side: balance per ledger (B10), plus unrecorded bank credits (B11), less unrecorded charges (B12), giving B13 = B10+B11-B12. Then:

B15:  =B8-B13
C15:  =IF(ROUND(B15,2)=0,"RECONCILED","OUT BY "&TEXT(B15,"#,##0.00"))

The other two sheets do the line work. Both have Date, Description, Amount, Matched? headers and a flag formula pre-filled to row 201 — 200 lines a side. On the Bank statement sheet:

=IF(C2="","",IF(COUNTIFS(Ledger!$C:$C,C2)>0,"matched","UNMATCHED"))

and its mirror on the Ledger sheet, looking back at 'Bank statement'!$C:$C. Filter either column D to UNMATCHED and you have your investigation list in about four seconds.

Three things amount-only matching gets wrong, and the template says so on the Reconciliation sheet itself:

1. Sign conventions. If the bank exports outflows as -500.00 and your ledger records them as 500.00, nothing matches. Normalise one side first — a helper column of =-C2, pasted back as values, is enough.
2. Duplicate amounts. Two payments of 250.00 on the bank side against one on the ledger side: COUNTIFS(...)>0 is true for both, so both read "matched" and the missing one hides. The difference in B15 still catches it, which is why you reconcile the total as well as the lines.
3. One-to-many. A deposit of 9,400 covering four invoices will never equal any single ledger line, so it stays UNMATCHED and needs a human or a name-based match — see fuzzy matching in Excel for the "ABC Corp" versus "ABC Corporation" problem.

To use it: paste the statement on one tab and the ledger on the other, both with amounts in column C, then work the UNMATCHED lines into the four adjustment cells (B6, B7, B11, B12) until C15 reads RECONCILED. Past 200 lines a side, copy D201 and paste down. Method and worked adjustments: bank reconciliation in Excel.

What the review above would find in it: four typed cells on the Reconciliation sheet (B6, B7, B11, B12) that are inputs by design, and a Matched? column whose formula stops at row 201 — which is a short range, and is the one the checks above would flag. It is deliberate and it is stated, but it behaves exactly like the defect: paste 260 lines and the last 59 are silently unchecked.

4. Month-end close checklist

Download the month-end close checklist — 1 sheet, no macros.

Twenty tasks in close order across # / Task / Owner / Status / Due day / Notes, in rows 8-27, with a period label in B4.

The tasks are the ones that actually hold up a close, sequenced Day 2 to Day 8: sales invoices raised and supplier invoices entered (Day 2), bank and card reconciliations, the payroll journal and a GRNI accrual (Day 3), deferred revenue, AR aging, prepaid release, bonus and leave accruals, asset additions and disposals (Day 4), bad-debt provision, depreciation and the stock count (Day 5), VAT/GST control account and intercompany elimination (Day 6), variance explanations and balance sheet movement review (Day 7), management pack and period lock (Day 8).

Status is a real data-validation dropdown on D8:D27 with four options — Not started, In progress, Done, N/A — and progress sits in E4:

=IFERROR(COUNTIF(D8:D60,"Done")/COUNTA(A8:A60),0)

Two consequences worth knowing. Tasks marked N/A stay in the denominator, so a month with three inapplicable tasks tops out at 85% — accept it as a convention or delete the rows you never use. And the ranges run to row 60 while the dropdown covers only D8:D27, so a task 21 added in row 28 needs an existing status cell copied down to bring the validation with it (how the dropdown is built).

To use it: set the period in B4, put a name in every owner cell — an unowned task is not a task — adjust the due days to your timetable, and save one copy per month rather than overwriting. The reasoning behind the sequence, and how to run it across a portfolio of client files: the month-end close checklist.

What the review above would find in it: the mismatch already described — formula ranges running to row 60 while the data-validation dropdown covers only D8:D27. Not an error, but exactly the kind of inconsistency between a formula's reach and a control's reach that check 5 exists to surface.

Wiring the four into one close pack

They hand off to each other. Put all four in a folder named for the period, then run them in this order:

1. Bank rec first — task 1 on the checklist is the reconciliation, and nothing downstream is trustworthy until the cash line is proved.
2. Ledger export into the P&L's Transactions sheet, expense cells on SUMIFS.
3. P&L, then carry net profit from B33 to the balance sheet's Current year profit cell, B39.
4. Balance sheet until row 43 reads OK - balanced in both columns.
5. Checklist updated as you go, so E4 is the honest status when someone asks.

Step 3 deserves a note, because it is the one place this pack creates the defect the review procedure hunts for: carrying net profit from the P&L to the balance sheet by hand is itself a plug. B39 becomes a typed number in a calculating block, exactly like the ones you were questioning in the client's file. There is no cross-workbook formula here to avoid an external link, which is the right trade — but it means the cell has to be checked every month. Write the number down, compare it to B33 on the P&L, and make that a line on the checklist rather than a thing you remember.

Keep the prior month's folder untouched. Comparatives re-keyed rather than carried forward are a common reason a variance column is wrong before anyone has looked at it — see variance analysis in Excel.

The schedules you should never accept as an inherited file

We ship four templates because those are the four we maintain. For the rest, a downloaded workbook is usually the wrong answer — and an inherited one is worse, for a reason the nine checks above cannot help you with.

Each of the five below encodes a policy judgement rather than a calculation. A depreciation register contains somebody's decision about useful life and part-year convention. A deferred revenue schedule contains somebody's decision about the recognition pattern. Those decisions are correct or incorrect for a business, not for a spreadsheet, and the review procedure cannot detect a judgement — only an error. A workbook full of the previous accountant's assumptions will pass all nine checks and still be silently applying a policy you have never agreed to.

Fixed asset and depreciation register. One row per asset — description, cost, date in service, method, life, residual — then a periodic charge with SLN, DB or a manual straight-line calculation, plus a net book value column that must agree to the balance sheet's property and equipment block. Part-year conventions and mid-life disposals are where most inherited registers stop reconciling: depreciation schedule in Excel.

Deferred revenue schedule. One row per contract, contract value spread across the recognition months, columns footing to the deferred balance. Genuinely dangerous to download, because the recognition pattern is a policy judgement rather than a formula: deferred revenue schedule in Excel.

AR and AP aging. A SUMIFS grid over an open-items list, bucketed 0-30 / 31-60 / 61-90 / 90+ on invoice date. Fifteen minutes from an export you already have, and it stays current because it recalculates rather than being re-typed.

Cash flow forecast. Thirteen weeks across, receipts and payments down, opening rolling into closing. A downloaded one rarely matches your payment runs, payroll dates or VAT quarters — the three things that decide whether it is worth reading.

Anything with a percentage column. Common-size statements, margin schedules, growth rates: quick mechanics, but the base is a judgement and the traps are real (percentage formulas for accountants).

Where HISAB 360 helps with the review

Most of the nine checks are keyboard shortcuts and take seconds. The two that do not scale are check 4 and the rebuild that sometimes follows it: on a six-tab workbook, finding every typed constant is a Go To Special away, but writing down where they all are, and then reconstructing a block as live formulas, is an afternoon.

HISAB 360 is a paid add-in for Windows desktop Excel with an AI chat panel docked inside the workbook, and three things it does bear directly on this page. You can ask it to scan a range and list every cell holding a typed constant rather than a formula, and write that list — addresses and values — out to a new sheet, which turns check 4 into a workpaper instead of a highlight. Once you have decided what a block should calculate, you can ask it to rebuild that block as live formulas in the sheet rather than writing them yourself. And because it connects to QuickBooks Online, Xero, Zoho Books, Odoo and FreshBooks, it can pull the same period straight from the client's ledger onto a tab beside their workbook — which is the only way to tie the file to something outside itself rather than checking it against its own internal consistency.

The rest of what it does surrounds the templates: it pulls invoices, bills, GL activity and contacts onto a sheet (the Transactions tab of the P&L template, populated without an export-download-paste cycle), writes back to create invoices, bills and journal entries, builds a P&L or balance sheet in the sheet from a trial balance, and turns a PDF bank statement or invoice into a table. Bank reconciliation runs as an automation with fuzzy matching on descriptions and amounts, picking up the variations an exact-match COUNTIFS cannot see — review what it matches before you post it.

Honest limits: Windows desktop Excel only (Microsoft 365 or Excel 2016+ on 64-bit Windows) — not Mac, not Excel on the web — and paid, with a 15-day trial that includes 50 AI credits and no card. Everything it generates deserves the review you would give a junior's schedule.

One thing it is not: it is a copilot in the workbook, and it does not form an opinion on a file. It can tell you that thirty-one cells in a range are typed constants. It cannot tell you whether that is a problem, and neither of you should treat anything it writes as sign-off.

Which one to start with

Frequently asked questions

Try HISAB 360 on your own workbook

HISAB 360 is an AI assistant inside Excel for accountants and finance teams — it writes macros, Power Query and formulas from plain English, and connects two-way to QuickBooks, Xero, Zoho Books, Odoo and FreshBooks. The 15-day trial is the full product, no card required.