KPO Knjiga Demystified: How to Track Revenue Correctly

Last updated: August 2026. Reflects current requirements under the Zakon o porezu na dohodak građana ("Sl. glasnik RS", br. 24/2001, consolidated through br. 6/2026) and the Pravilnik o poslovnim knjigama i iskazivanju finansijskog rezultata po sistemu prostog knjigovodstva ("Sl. glasnik RS", br. 140/2004 i 44/2018 – dr. zakon).

Every Serbian paušalac must maintain a KPO knjiga — the Book of Realized Turnover. It's your only mandatory bookkeeping obligation and the primary document the Tax Authority uses to verify your revenue. Despite being a simple ledger, the KPO generates a surprising amount of confusion. Paušalci routinely record things that don't belong, omit things that do, use wrong exchange rates, and sometimes don't maintain one at all.

This guide covers everything you need to know: what the KPO is, what goes into it (and what absolutely doesn't), how to handle foreign-currency invoices, paper vs electronic format, and the seven most common errors that draw attention from the Poreska uprava.

What is the KPO knjiga?

The Knjiga o ostvarenom prometu (KPO) — literally "Book of Realized Turnover" — is a chronological register of every invoice you issue. Think of it as a revenue log. You record each invoice as you issue it, with basic details: date, description, amount.

That's it. There is no expense tracking, no balance sheet, no profit-and-loss statement. Paušalci are specifically exempt from full bookkeeping — the KPO is the simplified alternative.

The legal basis is ZPDG čl. 43 st. 4 — "Preduzetnici paušalci dužni su da vode samo poslovnu knjigu o ostvarenom prometu" — together with the Pravilnik o poslovnim knjigama i iskazivanju finansijskog rezultata po sistemu prostog knjigovodstva ("Sl. glasnik RS", br. 140/2004 i 44/2018 – dr. zakon). Its čl. 3 st. 3 prescribes the KPO form; its čl. 7 prescribes what goes in it. There is no separate KPO rulebook: the KPO is one of the forms in the simple-bookkeeping rulebook, printed as an annex to it.

What goes into the KPO

The form has five columns, prescribed by čl. 7 of the Pravilnik:

Column 1 — Redni broj (sequential number) A running count from the start of the year: 1, 2, 3, and so on. It resets to 1 on January 1, or on the day you start trading if that falls later in the year. The rulebook adds a detail most guides omit: the same number must be written in the top right-hand corner of the underlying document — the invoice the entry is based on.

Column 2 — Datum i opis knjiženja (date and description of the entry) Date and description share a single column. The description identifies the transaction: "Web development services for Company X, Invoice #2025-047." No elaborate detail is needed.

For the date, use the datum prometa — the date the service was delivered or the goods supplied. For a service delivered across a period (a monthly retainer, say), that is normally the last day of the period. This date determines which calendar year and which rolling 12-month window the revenue falls into.

Columns 3 and 4 — Prihod od proizvoda / prihod od usluga The amount, split by what earned it: revenue from products sold in column 3, revenue from services performed in column 4. A paušalac who sells only services fills column 4 and leaves column 3 empty. Amounts are in dinars; a foreign-currency invoice is converted first (see below).

Column 5 — Ukupno (total) The sum of columns 3 and 4 for that row.

That's the entire structure. Five columns. One row per invoice.

What does NOT go into the KPO

This is where most mistakes happen. The KPO records only revenue from your business activity. The following items must never appear in it:

Expenses and costs. You bought a laptop for work? A plane ticket to visit a client? These are not revenue. Paušalci don't track expenses in any official capacity — the paušal system assumes a standardized expense deduction built into the tax formula.

Loan proceeds. If you received a business loan, that's not turnover. Don't record it.

Refunds or reversed transactions. If a client overpaid and you returned the excess, you need to record a storno (reversal) entry, not add the refund as a negative expense.

Interest income. Bank interest earned on your business account balance is not business turnover from your registered activity.

Private income. Salary from an employer (if you're running paušal as a side business), rental income, investment returns — none of these belong in the KPO.

The golden rule: if it's not an invoice you issued for your registered business activity, it doesn't go in the KPO.

Paper vs electronic KPO

You have two options, and the rulebook permits both.

Paper KPO

Purchase a physical KPO book from a bookstore or stationery shop (they're sold pre-formatted). Entries must be made in ink. Corrections require crossing out the error with a single line (so the original remains readable), writing the correct entry, and adding a note with the date of correction. No white-out, no erasing.

Electronic KPO (Elektronska knjiga)

Electronic keeping is explicitly permitted, and has been since the rulebook took effect — not since 2020. Čl. 4 st. 1 allows business books to be kept in loose leaves, bound, or "prenete na neki od medijuma automatske ili mikrografske obrade podataka, tako da se po potrebi mogu odštampati ili prikazati na ekranu": transferred to a medium of automatic data processing, so that they can be printed or displayed on screen when needed. Nothing in the rulebook requires routine printing.

So a spreadsheet, a dedicated app, or any digital format that preserves the prescribed structure — the five columns above — satisfies the rule. What you must be able to do is produce the book when an inspector asks, on screen or on paper. A format with an audit trail (a spreadsheet with version history, or a bookkeeping tool) is easier to defend than a freely editable document.

Certification (overavanje): what the rulebook says, and what is unsettled

Čl. 4 st. 3 of the Pravilnik still reads that the books under čl. 3 st. 1 and st. 3 — the latter being the KPO — "overavaju se kod nadležnog poreskog organa pre početka knjiženja": they are certified by the competent tax authority before bookkeeping begins. That is a before-you-start rule, not an annual one. The rulebook prescribes no yearly re-certification, and on its face the sentence does not distinguish a paper book from an electronic one.

Whether the Poreska uprava still performs this certification in practice is unsettled. Published guidance splits several ways — some sources describe stamping as routine, others report that branches no longer do it at all — and we have found no primary source that settles current practice either way. Do not assume an annual obligation, and do not assume the requirement has quietly lapsed. If you intend to keep a paper book, ask your local branch what it expects before you write the first line in it.

Foreign-currency invoices: the conversion rule

If you invoice in EUR, USD, or any other currency, the amount goes into the KPO in dinars. The type of rate is prescribed: for bookkeeping and statistics the law requires the NBS official middle rate, zvanični srednji kurs (Zakon o deviznom poslovanju čl. 41 st. 2). Which day's middle rate applies is not prescribed for a non-VAT paušalac — the KPO rulebook lays down no conversion rule at all — so converting at the datum prometa is settled practice rather than a statutory command. Apply one convention to every invoice and keep it consistent year to year; this guide uses the datum prometa throughout.

Example: You issue an invoice for €2,500 with a service date of October 15, 2025. The NBS middle rate on October 15 is 117.35 RSD/EUR. Your KPO entry records 293,375 RSD (2,500 × 117.35).

A few important points:

• Use the middle rate (srednji kurs), not the buying or selling rate.
• Having chosen the datum prometa convention, apply it consistently: not the date the client paid, and never the rate your bank applied during conversion — that last one is the part the law does settle.
• The difference between the NBS middle rate and the rate your bank actually applies when converting the incoming payment is called a kursna razlika (exchange rate difference). This difference is irrelevant for KPO purposes.
• If the NBS didn't publish a rate on that specific date (weekend or holiday), use the rate from the last business day before it.

Storno entries: correcting or canceling invoices

If you need to cancel or correct a previously recorded invoice, you make a storno entry in the KPO. This is a new line with the next sequential number, referencing the original entry, with a negative amount.

Example:

• Entry #23: Invoice #2025-023, October 10, Web development for Client X, 250,000 RSD
• Entry #24: STORNO of Entry #23, October 15, Cancellation of Invoice #2025-023, -250,000 RSD

If you're correcting the amount rather than canceling entirely:

• Entry #24: STORNO of Entry #23, -250,000 RSD
• Entry #25: Corrected Invoice #2025-023-R, 230,000 RSD

The 7 most common KPO mistakes

Based on forum discussions, Tax Authority inspection reports, and questions from the paušalci community, these are the errors that cause the most problems:

Mistake 1: Recording expenses

The KPO is income-only. No office rent, no equipment purchases, no travel costs, no subscriptions. Paušalci occasionally start recording expenses "just in case" or because they think it will help at tax time. It won't — and it confuses your revenue total.

Mistake 2: Recording bank-to-bank transfers

Transferring 200,000 RSD from your business account to your personal account is not revenue. It's your own money moving between your own accounts. Recording it inflates your apparent turnover and can push you closer to (or over) the revenue limits.

Mistake 3: Using the wrong exchange rate

Three common sub-errors here:

• Using the bank's conversion rate instead of the NBS middle rate
• Using the rate on the payment date instead of the service date
• Using a rate from a random currency converter website instead of the official NBS rate

Mistake 4: Not converting foreign invoices at all

Some paušalci record EUR invoices as-is: "€3,000" in the amount column. The KPO must be in RSD. Every foreign-currency amount must be converted.

Mistake 5: Breaking chronological order

KPO entries must be in strict chronological order by service date. If you issue Invoice #50 on March 15 and Invoice #51 on March 10 (for a service delivered earlier), the KPO must record Invoice #51 first (March 10) and Invoice #50 second (March 15).

Mistake 6: Not maintaining the KPO at all

Some paušalci — particularly those with only a few invoices per year — simply don't keep a KPO, assuming it's optional or that their bank statements are sufficient. The KPO is mandatory.

Mistake 7: Guessing about overavanje

Two guesses circulate, and both are guesses: that a paper book must be re-certified by the tax office every January, and that certification stopped being a thing years ago. The rulebook says certification happens before bookkeeping begins (čl. 4 st. 3), says nothing about repeating it annually, and current practice is not documented in any source we can verify. Ask your branch rather than inferring, and keep whatever they tell you together with the book.

KPO and tax inspections

During a poreska kontrola (tax inspection), the inspector will typically request:

1. Your KPO knjiga (paper or electronic printout)
2. Copies of all invoices referenced in the KPO
3. Your bank statements for the same period

The inspector cross-references these three sources. Invoices should match KPO entries (same dates, same amounts after conversion). Bank statement deposits should correspond to invoiced amounts (allowing for exchange rate differences and payment timing).

The best defense during an inspection is a clean, chronological KPO that matches your invoices exactly.

Key takeaways

1. KPO records only income from your business activity. Never expenses, transfers, loans, or personal income.
2. Five columns (Pravilnik čl. 7): sequential number; date and description of the entry; revenue from products; revenue from services; total. Not four.
3. Foreign invoices must be converted to RSD at the NBS official middle rate — the rate type the law prescribes (ZDP čl. 41 st. 2). Which day's rate applies is not prescribed for a non-VAT paušalac; this guide uses the service date, and consistency matters more than the choice.
4. Electronic keeping is explicitly allowed (Pravilnik čl. 4 st. 1) and no routine printing is required — the book must simply be producible on screen or on paper when asked. Certification under čl. 4 st. 3 happens before bookkeeping begins, not annually, and whether the tax office still performs it is unsettled.
5. Chronological order is mandatory. Sort by service date, not invoice number or issue date.
6. Never modify existing entries. Use storno (reversal) lines for corrections and cancellations.
7. The KPO total is your official revenue for limit calculations. Keep it accurate and you'll never be surprised by a Tax Authority inquiry.