When to issue a correction

An invoice already sent to KSeF can only be fixed with a correcting invoice. The original document stays in the system — a correction doesn’t delete it, only changes its effect.

Correction vs. cancellation

	When	What happens to the original invoice
Cancellation	Before the document reached KSeF and the counterparty	It disappears; the number is left unused
Correction	After it was sent to KSeF	It stays; the correction refers to it and changes its effect

In practice: if an invoice has a KSeF number, a correction is the only route.

Most common reasons

• An error in price or quantity — the correction changes the amounts.
• An error in the counterparty’s details — the correction changes the details, the amounts stay.
• A returned item or a discount after the sale — the correction reduces the taxable base.
• A price increase after issuing — the correction increases the taxable base.

What a correction can fix

The first step of the correction wizard asks exactly what needs fixing. The scope you choose decides which fields the wizard offers in the next step:

Scope	Covers	Availability
Line item prices and quantities	Unit price, quantity — Atestio recalculates VAT and totals.	Available
Adding or removing a line item	A missing item or one added by mistake.	Available
Seller’s details	Name, address — the NIP can’t be changed with a correcting invoice.	Available
Buyer’s details	Name, main and additional address — without changing the NIP.	Available
Line item VAT rate	E.g. 23% was charged instead of 8%.	Coming soon
Line item descriptions	Name, unit, PKWiU / GTIN / CN.	Coming soon
Dates	Delivery date or the period the invoice covers.	Coming soon
Payment terms	Due date, payment method, account.	In development
Wrong invoice number	Entering the correct number of the original invoice.	In development
Zero out the whole invoice	An invoice issued by mistake — see Cancelling a wrongly sent invoice.	Available

Scopes marked “Coming soon” and “In development” are announced in the wizard, but can’t be selected yet.

NIP

A correction never changes the seller’s or buyer’s NIP. A wrong NIP requires zeroing out the invoice and issuing a new one — see Cancelling a wrongly sent invoice.

How to issue a correction in Atestio

1. Open the invoice the correction concerns.
2. Choose Correction… (on a phone: More → Issue correction…) and confirm with Continue to correction. A correction is a new document in KSeF, so Atestio asks first.
3. Pick the correction’s scope from the table above and change the items it concerns.
4. Atestio prepares the document, fills in the reference to the original invoice, and sends it to KSeF.

Unchanged items stay unchanged — the correction shows the before and after values.

Correcting more than one invoice at a time is done with the bulk correction wizard — see Bulk corrections.

Which period a correction is recognized in

On the sales side, the rule depends on the correction’s direction. A correction that reduces the taxable base is, as a rule, recognized in the period in which the conditions for the reduction were agreed and met — not in the period of the original invoice. A correction that increases the base is recognized in the period in which the reason for the increase arose.

On the purchase side, things are different, and Atestio deliberately doesn’t resolve this automatically:

Do potwierdzenia przez doradcę. Poniższa informacja nie została jeszcze potwierdzona i nie należy jej traktować jako wiążącej wykładni. W razie wątpliwości skonsultuj się ze swoim księgowym lub doradcą podatkowym.

The type of correction declared by the seller does not determine the period in which the buyer should recognize the reduction in input tax. Art. 86(19a) of the VAT Act ties the reduction to the moment the conditions for the reduction were agreed and met — and those are circumstances on the buyer’s side, unknown to the invoice’s issuer.

That’s why, for purchase-side corrections, Atestio shows the period as a suggestion and holds the document for the taxpayer’s decision, instead of posting it automatically.

Oczekuje na: Q44 — tax advisor, question sent

What’s next

• Cancelling a wrongly sent invoice
• Bulk corrections
• Issuing your first invoice
• JPK_V7M — what Atestio fills in automatically