Korea VAT Deadline Checklist:
Tax Invoice Data Prep Before the 25th

The Four Deadlines: Korea's VAT Filing Calendar

Korea splits the tax year into two six-month periods (기), each subdivided into a preliminary return (예정신고) and a final return (확정신고). Corporate taxpayers file four times per year. Individual general taxpayers file twice, with preliminary periods covered by an NTS assessment notice (예정고지) instead of a self-filed return.

Small corporations with supply value (공급가액) below ₩150 million in the prior period are exempt from preliminary filing — the NTS sends an assessment notice for 50% of the prior period's tax instead. If the 25th falls on a weekend or public holiday, the deadline shifts to the next business day. In 2025, the January 25 deadline moved to January 27 (Monday); October 25 moved to October 27.

The critical point most filing guides skip: the tax invoice issuance deadline (세금계산서 발급 기한) falls on the 10th of the month following the supply date. That means June invoices must be issued by July 10 — and the Period 1 final return is due July 25. Fifteen days is all the buffer between the last invoice arriving and the filing cutoff. For AP teams, this compression is where mistakes happen.

What Missing the Deadline Actually Costs

Korea's penalty structure for VAT non-compliance is layered — multiple surcharges can stack on top of each other for a single missed filing. Under the Framework Act on National Taxes (국세기본법) Articles 47-2 through 47-5 and the VAT Act (부가가치세법) Article 60, three categories of penalties apply:

These are just the filing penalties. Tax invoice-specific surcharges under VAT Act Article 60 add another layer:

The penalty math explains why the data preparation phase matters more than the filing click itself. A single field error — a transposed digit in a 10-digit business registration number (사업자등록번호) — can cascade into a rejected input tax deduction (매입세액 불공제), which the finance team discovers only when the NTS sends a correction notice months later. For a deeper look at the cost structure of these errors, see the real cost of manual tax invoice entry for Korean finance teams.

The Four Fields That Must Be Right

Every Korean tax invoice contains four mandatory fields (필요적 기재사항) defined by VAT Act Article 32. If any one of these is missing, incorrectly recorded, or mismatched with the NTS e-Tax Invoice (전자세금계산서) system records, the invoice may be treated as improperly issued — and the buyer loses the input tax deduction.

These four fields are the minimum. In practice, AP teams also extract item descriptions, quantities, unit prices, and the 24-digit NTS approval number (승인번호) for electronic invoices. But it is the four mandatory fields that determine whether an invoice is legally valid for deduction. For a step-by-step guide on extracting these fields into a spreadsheet, see how to extract Korean tax invoice data to Excel.

The Two-Week Countdown: D-14 to D-Day

Most VAT filing stress comes from compressing weeks of data work into the final three days. Structuring the preparation into a two-week countdown distributes the workload and surfaces problems early enough to fix them.

D-14 to D-10: Collect and Match

• Pull all e-tax invoices from HomeTax. Log into HomeTax and download the full list of purchase e-tax invoices (매입 전자세금계산서) for the period. Compare the count against your internal AP records. Missing invoices at this stage can still be requested from suppliers.
• Gather paper tax invoices. Any supplier still issuing paper invoices (종이세금계산서) — permitted for individual businesses below the ₩80 million electronic issuance threshold — must be separately collected, scanned, and their data entered. This is where the bottleneck sits for companies with mixed-format invoice flows.
• Run a supplier count reconciliation. Count the number of unique supplier registration numbers in your records versus HomeTax. A mismatch means either a missing invoice or a duplicate entry.

D-9 to D-5: Validate Fields

• Verify the four mandatory fields on every invoice against the checklist above. Prioritize high-value invoices (₩10 million+) — an error on a large invoice has proportionally larger consequences for input tax deductions.
• Separate non-deductible items. Entertainment expenses (접대비), personal-use vehicle costs, and purchases without proper documentation (적격증빙) are not eligible for input tax deduction even with valid invoices. Flag these before they inflate your deduction claim.
• Check for credit card overlap. If a transaction was paid by credit card and a tax invoice was issued for the same supply, reporting both as separate sales entries will overstate your revenue. The credit card transaction must be excluded when the tax invoice is the reported evidence.

D-4 to D-1: Compile and Review

• Generate the purchase invoice summary table (매입처별 세금계산서합계표). This aggregates all purchase invoices by supplier, listing each supplier's registration number, invoice count, total supply value, and total VAT. If your ERP — whether Douzone WEHAGO (더존 WEHAGO), ECOUNT (이카운트), or another system — supports automatic generation from entered data, run it now and manually spot-check against the source documents.
• Reconcile output tax (매출세액) vs. input tax (매입세액). The VAT payable or refundable amount is the difference. If input exceeds output, you have a refund claim — verify the refund bank account is registered in HomeTax.
• Pre-fill the return in HomeTax. The electronic filing system (전자신고) lets you load e-tax invoice data automatically and manually add paper invoice totals. Complete the form a day early; review it fresh the next morning before submitting.

The countdown works because it separates collection from validation from compilation — three distinct tasks that fail when compressed into one frantic weekend.

Where the Real Bottleneck Sits

For companies processing fewer than 20 invoices per quarter, the countdown above is manageable with manual data entry. The process breaks down at scale — and it breaks down at a specific point: extracting data from invoices that are not already structured.

Electronic tax invoices (전자세금계산서) transmitted through the NTS system arrive as structured XML data. HomeTax can aggregate these automatically. The bottleneck is everything else: paper invoices scanned to PDF, invoices received as image attachments in KakaoTalk or email, supplier statements that bundle multiple transactions onto one page, and corrected invoices (수정세금계산서) that require matching against the original.

A semiconductor company's finance team described the pattern: the tax invoice issuance deadline (the 10th) and the VAT filing deadline (the 25th) fall in the same month, creating a two-week window where the accounting team is simultaneously verifying last month's invoices and preparing the current quarter's return. When 150 invoices arrive from 40 suppliers in mixed formats — some electronic, some scanned PDFs, some photographed on a phone — the limiting factor is not the filing itself, but the hours spent re-entering supply values and registration numbers from images into a spreadsheet. When volumes cross that threshold, the data extraction step becomes the rate limiter. To see how batch processing works in that scenario, read how to batch-process Korean tax invoices for VAT reporting.

Extracting Tax Invoice Data Without Retyping

ImageToTable.ai approaches the extraction problem differently from template-based OCR tools. Instead of requiring you to define pixel coordinates or train on sample documents, it uses a vision language model that reads the document the way a human does — by understanding what each field means, not where it sits on the page.

In practice, this means you define the column names you want in your output spreadsheet — such as "Supplier Name," "Business Registration Number (사업자등록번호)," "Supply Value (공급가액)," "VAT Amount (세액)," "Issue Date (작성연월일)" — and the AI locates each value anywhere on the invoice by interpreting the field semantically. You type the column headers you need; the AI fills in the rows. This is what Custom Column Extraction means: the column names you enter become the exact headers of your output table, and the AI reads each document to find the corresponding values.

This matters for Korean tax invoices specifically because the document format varies. NTS-standard electronic invoices follow a consistent layout, but scanned paper invoices from small suppliers, handwritten corrections, and multi-page bundled statements do not. A template-based tool would need a separate template for each variation. A semantic extraction tool reads them all with the same set of column definitions.

For quarter-end preparation, the batch processing mode is where the time savings compound. Upload all 50, 100, or 150 invoices at once, apply the same column definitions, and export to a single Excel file — each invoice becomes one row, each defined column becomes one column header. The output is a ready-made input for the purchase invoice summary table (매입처별 세금계산서합계표) or for direct import into your ERP.

From Extracted Data to Filed Return

The extracted spreadsheet is the bridge between raw documents and the ERP or HomeTax filing form. The workflow depends on which system your team uses:

The critical step is the handoff: once tax invoice data is extracted into a structured spreadsheet, it maps directly onto the fields that ERPs and HomeTax expect — supplier registration number, supply value, VAT amount, invoice count per supplier. No reformatting, no re-keying. The extraction output becomes the ERP input.

For teams that process invoices into Google Sheets rather than a desktop ERP, ImageToTable.ai also offers a Google Sheets add-on that writes extraction results directly into the active spreadsheet — useful for smaller operations that manage their purchase ledger in Sheets.

Frequently Asked Questions

Can I file a VAT return late and pay the penalties instead?

Technically yes, but the penalties compound. Non-filing costs 20% of the tax due immediately, plus 0.022% per day on the unpaid amount. Filing even one day late costs less than filing 30 days late — the late payment interest alone on a ₩10 million tax liability is ₩2,200 per day (₩66,000 per month). A voluntary late filing (기한후 신고) also qualifies for reduced surcharges under Framework Act on National Taxes Article 48: 50% reduction if filed within one month, 30% within three months, 20% within six months.

What if a supplier hasn't issued a tax invoice by the filing deadline?

You cannot claim the input tax deduction without a valid tax invoice. If the supplier fails to issue, you can apply for a buyer-issued tax invoice (매입자발행 세금계산서) through HomeTax — but this requires supporting documentation (거래명세서, payment confirmation) and NTS approval. The supplier faces a 2% non-issuance surcharge on the supply value.

Are paper tax invoices still accepted?

Yes, but the scope is narrowing. Since July 2024, all corporations and individual businesses with prior-year revenue of ₩80 million or more must issue electronic tax invoices. Paper invoices are only valid from suppliers below that threshold. If you receive paper invoices, you must separately report them in the paper invoice section of the purchase summary table — they will not appear in the HomeTax electronic records automatically.

Does ImageToTable.ai handle both electronic and scanned paper tax invoices?

Yes. The extraction works on PDF, JPG, PNG, and WebP inputs. Electronic tax invoices downloaded as PDF from HomeTax and paper invoices photographed with a phone camera can be uploaded in the same batch. The AI reads each document independently based on the column definitions you provide — it does not rely on a fixed template, so format variation across suppliers does not require separate configuration. Recognition accuracy for printed table data reaches up to 99%, and processing time is 5–10 seconds per page compared to roughly 3 minutes of manual entry.

What columns should I define for Korean tax invoice extraction?

For VAT filing preparation, the minimum set is: Supplier Name, Supplier Registration Number, Supply Value, VAT Amount, Total Amount, Issue Date. For more granular reconciliation, add: Item Description, Quantity, Unit Price, NTS Approval Number. You can also add a computed column — for example, "VAT Check (Supply Value × 10%)" — to automatically flag invoices where the stated VAT does not equal exactly 10% of the supply value. The AI performs this calculation during extraction and outputs the result alongside the extracted fields.