Why a month goes missing in the first place

A missing month in a net worth spreadsheet is almost never a calculation problem. It is a data-entry and structure problem. Most trackers record balances on a reporting date, subtract what you owe from what you own, and then repeat the process the following month ^[S1]. When a month disappears, one of three things usually happened: the row was never created, the row was created but its date or formula broke the history, or the row exists but sits outside the range your chart and summary formulas read.

It helps to separate two jobs that people often blend together. A budget records money earned and spent over a period, while a net worth tracker records balances at a single point in time ^[S1]. A missing month in a net worth sheet therefore means you are missing a snapshot, not a transaction log. That distinction matters because it tells you where to look: at your date column and your account balance rows, not at your spending categories.

The guide below walks through diagnosis, repair, and prevention. Exact menu names and formula behaviour vary between Excel, Google Sheets, and LibreOffice, and features do change over time, so treat interface instructions as general guidance and check your own version’s help files if a command is not where you expect it.

Step 1: Confirm whether the month is truly missing

Before editing anything, work out which kind of gap you have. A month can be absent from the data, present in the data but invisible on a chart, or present but wrong. Each has a different fix.

Check the following in order:

• The date column. Sort your history block by date and look for a jump, for example from 31 January straight to 31 March. If the February row is gone, you have a genuine data gap. Label a block of rows with a Date column next to your Net Worth formula and copy the formula pattern down each time you add an entry; doing this consistently is what keeps the history intact ^[S2].
• Rows hidden or filtered. A filtered view or a group of hidden rows can make a month look absent. Clear filters and unhide all rows before concluding anything.
• Chart and summary ranges. A chart series or a lookup formula may stop one row short of the newest data. If February exists in the sheet but not on the graph, the range is the culprit, not the data.
• Text instead of dates. A date typed as text, or in a different format from the rest of the column, will sort incorrectly and can be skipped by formulas. Compare the cell’s alignment and format with neighbouring rows.
• Duplicate or overwritten rows. Sometimes a new month is typed over the previous one. If January’s figures look suspiciously like December’s, check whether an entry was overwritten rather than added.

Writing down which of these applies saves you from “fixing” a sheet that was only filtered.

Step 2: Rebuild the missing snapshot correctly

If the month really is absent, you need to reconstruct it. The important principle is consistency: the useful work in a net worth tracker is keeping the dates, the account list, and the valuation method consistent ^[S1]. A reconstructed month that uses different accounts or a different valuation approach will distort your trend line even if every individual number is accurate.

Use this practical sequence:

1. Pick the correct reporting date. Match the day of the month used by your other rows, whether that is month-end or payday. Do not mix conventions within one history.
2. Use the same account list. Copy the account names from the adjacent month rather than retyping them. Missing debts are one of the classic errors that make a working spreadsheet give a misleading answer ^[S1], and a rebuilt month is exactly where an account gets dropped.
3. Gather statements or screenshots for that date. Retrieve the balance for each asset and each liability as of the reporting date. If a statement is unavailable, use the closest reliable figure and note the approximation in an adjacent comment cell rather than silently guessing.
4. Copy the formula, do not retype it. Duplicate the previous month’s formula across the new row so the calculation logic is identical. Retyping is how sign errors and range errors creep in.
5. Reconcile the result. Compare the reconstructed net worth with the months either side. A figure far outside the surrounding trend usually signals a missing debt, a double-counted asset, or a transfer recorded as new wealth. Counting home equity twice and treating transfers as new wealth are both known ways a functioning spreadsheet produces a misleading answer ^[S1].

If you cannot reconstruct the month with confidence, an honest alternative is to insert the row with a clear “estimate” label, or to leave the gap and note why. A labelled gap is less damaging to your analysis than a fabricated snapshot presented as fact.

Step 3: Fix the formulas, chart, and history range

Once the row exists, make sure everything downstream sees it. This is where many people stop too early, add the missing month, and then wonder why the chart still shows a gap.

If your sheet uses a table object rather than a plain range, typing in the row directly beneath the last entry often extends the table automatically, but this behaviour differs between applications and versions, so verify by checking whether the new row inherits the formula. In Google Sheets, array formulas and query-based summaries can also fail to pick up inserted rows if the source range was hard-coded.

After the repair, recalculate and compare the new month against both neighbours. If the trend line now looks continuous, the fix is probably complete. A trend line is valuable precisely because it catches a debt creeping up long before any single month’s snapshot reveals it ^[S2], and that only works if every month is present and comparable.

Step 4: Prevent the next gap

The most reliable fix is structural. A tracker that requires you to remember to add a row will eventually miss one. A tracker that makes the next row obvious will not.

• Pre-build the date column. Fill the next twelve month-end dates in advance. The empty rows act as a visible reminder and keep chart ranges stable.
• Keep one row per reporting date. Label the date column next to the net worth formula and copy the full formula pattern down whenever you add an entry ^[S2].
• Add a completeness check. A simple helper cell can count the rows in the current year and compare them with the number of months expected, flagging any shortfall.
• Separate snapshots from cash flow. Keep budget data out of the net worth block. Your salary belongs in a budget; the money still in your bank account on the reporting date belongs in net worth ^[S1]. Mixing the two creates rows that look like months but are not snapshots.
• Record the valuation method. A short note on how each account is valued, and when it was last updated, prevents future-you from reconstructing a month with the wrong basis.
• Back up before editing. Duplicate the file before inserting rows or changing formulas, so a failed repair is reversible.

Finally, decide deliberately whether your sheet is a history or a snapshot. A spreadsheet is the right tool if you want full control over which accounts count and how the history is stored, and you do not mind updating each balance yourself ^[S2]. If you only ever need the current number, a simpler design with no history column will never develop a missing month at all. But if you want to see the direction of travel, commit to the history block and protect it with the habits above.

A short checklist for the next time it happens

Sort by date to confirm the gap; check filters and hidden rows; verify date formats; rebuild the row using the same accounts, date convention, and valuation method; copy rather than retype the formula; extend chart and summary ranges; reconcile against neighbouring months; and note any estimate openly. Done in that order, a missing month is usually a fifteen-minute repair rather than a rebuild. The underlying arithmetic is short — assets minus debts on a consistent date ^[S1] — so the effort belongs in keeping the structure consistent, which is exactly what prevents the problem from recurring.