Frequently Asked Questions
What is COGS (cost of goods sold)?
COGS is what the goods you sold in a period cost you. In Türkiye it is needed to calculate gross profit for provisional tax returns (geçici vergi). It is derived from opening stock, purchases during the period and closing stock.
Which costing methods are allowed in Türkiye?
Under the Turkish Tax Procedure Law (Vergi Usul Kanunu), actual cost, weighted average cost and first-in-first-out (FIFO) may be used. Mizan supports weighted average and FIFO. Ask your accountant which method suits you.
Where do I download my e-invoice XML files?
If you use Turmob Luca, download them from the e-fatura/e-arşiv module; if you use the GİB portal, download them via the İnteraktif Vergi Dairesi. You need both your purchase and sale invoices.
Is my invoice data uploaded anywhere?
No. Mizan runs entirely in your browser. Your files are never sent to any server and are never stored anywhere. You can even use it with your internet connection switched off.
Product names differ between my purchase and sale invoices — what happens?
This is very common. Mizan detects likely matches and proposes them for your approval. Your matches are stored in your browser, but to use them on another computer — or after clearing your browser data — you need to download your backup file and load it back.
What is the cost of my service invoices?
Services such as consultancy or maintenance have no stock cost. You can mark these products as 'service'; their COGS becomes zero and their revenue is shown separately in the report.
Can I use PDF invoices as well?
Yes, but XML is preferred. XML is structured data, so every field is read exactly. A PDF is a rendered document; Mizan reads it by inferring rows and header labels, so there is a margin for error. Invoices read from PDF are badged in the list and the report, and marked in a separate 'Source' column in the Excel export — you are expected to check those figures against the document. A file that cannot be read is rejected rather than guessed at, and manual entry is offered instead.
Do I have to redo everything next quarter?
No. From the Settings step you can download all your work as a single backup file (.mizan): invoices, product matches, opening stock and your settings. Next period you load that file and add the new invoices on top — no need to redo the matching. Loading a backup replaces what is currently there, so the flow is one chain: load the backup, add new invoices, download a fresh backup.
How do I choose the reporting period?
On the Report step you can enter a date range by hand or pick a quarter with the Q1–Q4 shortcuts. Sales are reported only for the period you choose; stock reflects every movement up to the period end, because a sale before the period still consumed goods.
Does it calculate VAT too?
Yes. The VAT tab in the report shows output and input VAT by month, the taxable base per rate, and the VAT payable. If you carry VAT forward from an earlier period you can enter it on the Settings step; it is applied to the first month. Lines with no stated rate are never guessed at — they are listed as a warning instead.
How do I enter opening stock or purchases with no invoice?
On the Settings step you can enter your opening stock with quantities and unit costs. For purchases you have no invoice for, you can add a manual purchase entry. Costs entered this way are flagged separately in the report, because they are not backed by a document.
Are return invoices handled correctly?
Yes. A purchase return is treated as stock going out, a sale return as stock coming back in. Quantities are never negative — a return flips the direction of the movement, not its sign.