[GNC] Balance sheet (multicolumn) shows Assets != Liabilities due to rounding of foreign currency amounts

[Tamar Hamlyn]

Two additional screenshots (adding foreign currency amounts and
exchange rates to both reports) might help show this more clearly,
please refer attached.


On Thu, 28 May 2026 at 19:32, Tamar Hamlyn <hamlynt at gmail.com> wrote:
>
> Hi GnuCash users,
>
> I searched the bug tracker but couldn't find this specific issue
> documented below.
>
> Kind regards,
> Tamar.
>
> Issue: Balance sheet (multicolumn) shows Assets != Liabilities due to
> rounding of foreign currency amounts
>
> Version
> -------
> GnuCash 5.15, macOS
>
> Issue
> -----
> Generating a balance sheet (multicolumn) can produce asset total !=
> liability total, due to rounding of foreign currency amounts. Standard
> balance sheet is unaffected.
>
> Steps to reproduce
> ------------------
> A test gnucash file with transactions below is attached.
>
> New book:
> Choose reporting currency: AUD
>
> New accounts under Current Assets:
> Bank 1(JPY)
> Bank 2(JPY)
>
> Existing Equity account:
> Opening balances(AUD)
>
> Transactions (entering the AUD quantity in the "to amount" field in
> the exchange rate window):
> Bank 1: JPY 500k / Opening balances: AUD 3,333.33
> Bank 2: JPY 200k / Opening balances: AUD 1,333.33
>
> Prices:
> Tools, Price Database, expand Currencies to JPY, add a new
> end-of-period exchange rate of:
> 2026-06-30: 0.00666665
>
> Note the slight exchange rate difference with the transaction-derived
> rate of 0.00666666. This difference is what triggers divergent
> rounding between the two reports.
>
> Run report:
> Balance sheet (multicolumn). Report Options, Commodities tab: set
> reporting currency to AUD, set price source to last up through report
> date.
> For comparison, also run standard balance sheet. Apply same report
> options in Commodities tab: set reporting currency to AUD, set price
> source to last up through report date.
>
> Actual behaviour
> ----------------
> Balance sheet (multicolumn) does not balance: assets != liabilities.
> Assets total from balance sheet report is: AUD 4,666.65
> Liabilities total from balance sheet report is: AUD 4,666.66
>
> Note the 1 cent difference. Balance sheet (standard) displays correct
> behaviour, assets and liabilities both total AUD 4,666.66.
>
> Desired behaviour
> -----------------
> Balance sheet should ALWAYS balance.
>
> If balance sheet totals do not match, this suggests an accounting
> error and invites questions about errors or inaccuracies. It makes the
> balance sheet report invalid by definition.
>
> Possible cause
> --------------
> The possible cause might relate to the multicolumn report using a
> round-then-sum approach, while the standard report uses
> sum-then-round.
>
> The current behaviour in balance sheet (multicolumn) is consistent
> with the following:
> - First convert child foreign currency amount to a corresponding
> (rounded) amount in reporting currency. This involves multiple
> conversions and applies rounding to every conversion.
> - Then sum the resulting rounded reporting currency amounts to produce
> intermediate and top-level reporting currency totals.
> This approach accumulates rounding errors at each level in the account
> hierarchy, which in turn results in the top-level discrepancy in
> totals. It is a round-then-sum approach.
>
> Possible fix
> ------------
> If strict equality between assets and liability is desirable, then
> balance sheet (multicolumn) report should instead do the following:
> - First, determine all intermediate and top-level foreign currency
> quantities, by aggregating all child foreign currency quantities at
> each point in the account hierarchy.
> - Convert each foreign currency total at each level in the account
> hierarchy to the reporting currency amount as a single conversion.
> Present these totals in the report.
> This sum-then-round approach only performs a single rounding operation
> as the last step at each level of the account hierarchy. This ensures
> that maximum accuracy is retained for account totals, as they are
> constructed directly from their local-currency components. Notably
> this approach does not re-use rounded subtotals to construct parent
> account amounts.
>
> Discussion
> ----------
> While the sum-then-round approach can ensure the balance sheet does
> balance, it also means that report subtotals and totals may not
> reflect the sum of their displayed sub-accounts and subtotals. Is it
> desirable to prioritise line-item consistency over balance-sheet
> equality?
>
> I'd be grateful for feedback from users or devs who have encountered
> this issue, or who are familiar with the development history, who have
> views either way on which approach might be preferred.
>
> Real-world impact
> -----------------
> The above rounding errors mean that a real-world balance sheet does
> not balance in approximately 5 out of the past 10 years. The accounts
> contain assets across around 6 foreign currencies, with relatively
> infrequent changes in holdings throughout the history.
>
> There are no specific triggers for the mismatched balance sheet
> totals, other than the randomness of rounding foreign currency
> subtotals and their conversion at the relevant exchange rates in
> effect at each balance sheet date.
>
> AI usage
> --------
> The explanation above was written by myself after testing the above
> steps manually in GnuCash. I then ran my draft through Claude which
> made minor changes to grammar and clarity of explanation.
>
> Attachments
> -----------
> 1 General Journal.png
> 2 Balance Sheet Multicolumn.png
> 3 Balance Sheet Standard.png
> 4 test-balancesheet-multicolumn.gnucash (XML)
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