Digitizing documents: scanner, OCR & formats

To digitize documents, offices mainly need three things: a document scanner with automatic feed and duplex scanning, fixed settings for resolution and format, and text recognition (OCR) that makes the files searchable. For text, around 300 dpi is sufficient, saved as PDF/A for long-term archiving. Anyone who wants to destroy paper records after scanning also needs a documented scanning procedure.

This article goes into more detail on the “scanning” step from the guide Digital filing in the company. Status: October 2026.

Which scanner is suitable?

Device	Strengths	Limitations	Suitable for
Document scanner with automatic document feeder (ADF)	fast, duplex, batch in one pass	not suitable for books and delicate originals	receipts, letters, contracts in everyday office use
multifunction printer	already available	often slow, weaker feed, settings hidden	occasional scanning
flatbed scanner	gentle, good quality	each page individually	Books, photos, bound documents
Smartphone app	always with you	Quality varies, not suitable for large volumes	Receipts on the go

For everyday office use, a dedicated document scanner with automatic feeder is almost always worthwhile: it processes a stack of mixed formats duplex in a single pass and can send files directly to a network folder or the filing system. Look for ultrasonic double-feed detection so that no pages are lost.

The correct settings

Resolution: 300 dpi for text documents. More only increases file size; less reduces text recognition quality.
Color mode: Grayscale or automatic color detection. Use color only where it matters, such as for stamps or markings.
Blank pages: have them removed automatically, otherwise files will grow with blank reverse sides.
One document, one file: Scan multi-page documents together; separator sheets or barcodes help with batch scanning.

File format: Why PDF/A

PDF/A is a standardized variant of PDF for long-term archiving. Fonts and color profiles are embedded, external dependencies excluded, so the file will still display the same way many years from now. For filing tax-relevant documents that must be retained for up to ten years, PDF/A is therefore the obvious choice. Images such as photos can remain as JPEG or PNG.

Important for e-invoices: the structured file (XML) is the original here. A PDF printout of it is not sufficient for retention, see Receive and process e-invoices.

OCR: Make scanned documents searchable

OCR (Optical Character Recognition, text recognition) identifies the text on a scanned image and stores it as an invisible text layer in the PDF. Only then can full-text search find the document and content be copied. Many scanners, document management systems, and open-source solutions such as Paperless-ngx perform OCR automatically on ingestion.

Modern AI goes one step further: it not only recognizes text, but also what the document is, for example an invoice from supplier X for amount Y, and suggests a filing location and keywords. How this works is shown in the article Paperless-ngx and AI.

Replacement scanning: When paper may be discarded

Paper documents may generally be destroyed after scanning if the scanning is carried out according to a documented procedure and the digital version is properly retained, meaning complete, unalterable, and retrievable. This includes a process documentation, which describes who scans and checks what and how. The German Chamber of Tax Advisors has published a sample procedural documentation for this purpose.

Excluded are documents that must be retained in their original form, such as annual financial statements and opening balance sheets; deeds such as notarized contracts are also better kept in the original. Clarify the details with your tax advisor. Background in the article Digital filing in accordance with GoBD.

The existing records: Scan everything?

Usually not. A cutoff date has proven effective: from then on, everything is captured digitally, and ongoing processes are included. Older files are only digitized if they are used regularly. For large volumes, an external scanning service provider can be more cost-effective than using your own working time.

The consulting and guided implementation is eligible for funding: Through INQA-Coaching the federal government covers 80% of consulting costs of up to €1,200 per day for up to 12 days, i.e. up to €11,520 in funding. In Mecklenburg-Western Pomerania and the other new federal states, the BAFA consulting grant with 80% eligibility (50% in the former West German states). The consulting is funded, not the software. Which program is suitable is shown by the Funding Check.

Frequently Asked Questions

At what resolution should I scan documents?

For text documents, 300 dpi is the usual standard. This is sufficient for good text recognition and keeps the files small. A higher resolution is only worthwhile for very small print or photos.

Which file format is suitable for archiving?

PDF/A, the standardized archival version of PDF. It embeds fonts and color profiles so that documents are displayed consistently over the long term. For e-invoices, by contrast, the structured XML file is the authoritative original.

What is OCR?

OCR stands for Optical Character Recognition, i.e. text recognition. It turns a scanned image into searchable text so that documents can be found via full-text search.

May I destroy originals after scanning?

In principle, yes, if scanning is carried out according to a documented procedure and the digital files are properly retained. Exceptions are documents that must be kept in their original form, such as annual financial statements. If in doubt, your tax advisor can clarify this.

Next step

If you want to do more than just digitize your documents and also automatically classify them and find them by asking questions, the page AI document search, shows what is possible. For an assessment, you can reach us via the contact page.