How to combine invoice pdfs for accounting and reconciliation
- Step 1Decide how to group the batch — Group by supplier, by approval run, or chronologically — whatever your AP workflow expects. Because the merge panel has no drag-to-reorder, the order you load files is the final order; a quick filename sort (e.g.
2026-06-03_AcmeCorp.pdf) makes the sequence predictable. - Step 2Collect the invoice PDFs — Download invoices from email attachments, supplier portals, or scanner output. Any valid PDF works regardless of which system or supplier produced it.
- Step 3Unlock any password-protected invoices first — Some suppliers email password-protected invoices. If a file needs a password to open, it can't be merged directly — strip protection first with PDF Remove Password (for files you're authorised to handle), then merge.
- Step 4Drop the invoices into the merger in order — Add files to PDF Merge in your chosen grouping. Each tile shows name, size, and page count, so you can verify the batch before running. Remove and re-add to fix any out-of-place invoice.
- Step 5Run the merge and download the batch — With at least two invoices queued, click Process. The engine appends every page in order into one new PDF, all locally. Download the batch (named from the first file, e.g.
AcmeCorp.merge.pdf). - Step 6Stamp for the audit trail and attach — For a referenceable record, run the batch through PDF Bates Numbering (e.g.
AP-000001) or PDF Page Numbers, then attach the single PDF to your approval workflow or upload to Xero/QuickBooks.
What the merge does to invoices
The merge is a page-assembly operation — it never parses invoice data. Grounded in the actual copy-pages behaviour.
| Aspect | Behaviour | AP implication |
|---|---|---|
| Invoice totals / line items | Never read or changed — pages are copied, not parsed | Numbers are exactly as the supplier sent them |
| Page quality | Preserved — no recompression | Logos, tables, and scans stay legible |
| Mixed page sizes | Preserved per page | A4 bill + Letter receipt coexist undistorted |
| Bookmarks / outline | Not carried over | Use page/Bates numbers for navigation |
| Form fields (AcroForm) | Not preserved as a working form | Flatten fillable invoice templates first |
| Title / author metadata | Not copied — batch starts clean | Set the batch's own metadata if needed |
Free vs. Pro for invoice batching
Real tier limits. The free batch cap is two files per run, once per day.
| Limit | Free | Pro |
|---|---|---|
| Invoices per merge | 2 (once per day) | Unlimited |
| Max size per invoice | 2 MB | 50 MB |
| Max pages per invoice | 50 | 500 |
| Data sent to a server | None | None |
Cookbook
AP batching patterns. Load order is batch order, so each example lists the exact load sequence.
Weekly approval run, grouped by supplier
Combine the week's invoices into one document for a single sign-off, ordered by supplier so the approver moves through them logically.
Load order: AcmeCorp_INV-1042.pdf AcmeCorp_INV-1043.pdf Globex_INV-88.pdf Initech_INV-7.pdf Merged: AP_week24.merge.pdf — one file to approve. (Free: 4 files — merge in two passes of 2, or use Pro.)
Receipts behind one expense report
A month of receipts stapled into one PDF to attach to a single expense claim. Sort chronologically.
Load order (by date): 2026-06-02_taxi.pdf 2026-06-09_hotel.pdf 2026-06-15_meals.pdf Merged: expenses_june.merge.pdf — attach to the claim. Totals untouched — merge never reads the amounts.
Bates-number an approved batch for audit
After approval, stamp a sequential reference across the whole batch so each page is uniquely identifiable in the audit trail.
Step 1: Merge → AP_batch.merge.pdf (18 pages)
Step 2: PDF Bates Numbering, prefix AP-, start 1, 6 digits
→ AP-000001 .. AP-000018, bottom-right
Each invoice page now has a unique, citable reference.Flatten a fillable invoice template before merging
A supplier sent a fillable PDF invoice. Flatten it so the entered amounts and details become permanent before they join the batch.
Step 1: PDF Flatten on Supplier_form_invoice.pdf
→ values baked in as static text
Step 2: Merge with the rest of the batch
Without flattening, the form fields wouldn't survive the merge.Compress scanned paper invoices to fit the free limit
Scanned paper bills can exceed 2 MB. Compress, then merge — fine for archival AP records.
Scan ≈ 2.8 MB (over free 2 MB cap) Step 1: PDF Compress (Aggressive), target 1 MB, per file Step 2: Merge the compressed scans + digital invoices Note: compression re-encodes scan images; the visible amounts remain readable but the page is no longer selectable text.
Edge cases and what actually happens
Worried the merge will change invoice totals
By designIt can't — the merge copies whole pages and never parses, reads, or rewrites the content on them. Totals, tax lines, PO numbers, and bank details are byte-for-byte identical to what the supplier sent. (If you need to *extract* invoice figures, that's a different tool: PDF Table to JSON or PDF to Excel.)
A supplier emailed a password-protected invoice
RejectedAn invoice that requires a password to open can't be read for merging and will fail to load. (Permission-only restrictions, like print-blocking, are ignored — those merge fine.) Remove the open password first with PDF Remove Password for invoices you're authorised to process, then merge.
More than 2 invoices in a batch on free tier
Limit reachedFree merging handles 2 files per batch, once per day — a weekly AP run usually has more. Merge in passes of two, spread across days, or upgrade to Pro for a single unlimited-file batch. Pro is the practical choice for any recurring AP merge.
An invoice exceeds 2 MB or 50 pages on free
Limit reachedEach free-tier file must be ≤ 2 MB and ≤ 50 pages. A high-resolution scanned bill can exceed the size cap. Shrink it with PDF Compress (Aggressive), or upgrade to Pro (50 MB / 500 pages per file).
Invoices ended up in the wrong order
By designThere's no drag-to-reorder — invoices merge in load order. Sort by filename before loading, remove and re-add a misplaced file, or rearrange the merged batch with PDF Reorder.
A fillable invoice template was merged
Form not preservedInteractive form fields don't survive the merge as a working form. Flatten the fillable invoice with PDF Flatten first so the entered amounts and details become permanent static content.
Scanned invoices aren't searchable in the batch
ExpectedMerging doesn't OCR — a scanned (image-only) invoice stays unsearchable in the batch. If you need to search the merged AP file by supplier or amount, run PDF OCR on it afterward to add a text layer.
Mixed A4 and Letter invoices look uneven
ExpectedEach invoice keeps its original page size, so European A4 bills and US Letter receipts in the same batch is normal and intended — nothing is scaled or cropped. If your archive needs uniform pages, normalise with PDF Resize after merging.
Frequently asked questions
Will merging change or alter my invoice totals or data?
No — and it can't. The merge copies whole pages without parsing, reading, or modifying their content, so every total, tax line, PO number, and bank detail is byte-for-byte identical to the supplier's original. Merging is purely page assembly; if you actually want to *extract* invoice figures into a spreadsheet, use PDF to Excel or PDF Table to JSON instead.
How secure is this for financial and supplier banking data?
Fully secure against upload exposure: the merge runs entirely in your browser using pdf-lib, so invoices — including any bank account or sort-code details — never reach a server. Only an anonymous run counter (no content) is saved when you're signed in, which you can opt out of. There is no server-side copy of your financial documents.
Can I merge invoices from different suppliers and layouts?
Yes. As long as each file is a valid PDF, invoices from any supplier, system, or layout combine into one batch — different fonts, logos, and page sizes are all fine. Each page is copied exactly, so every invoice looks identical to its standalone version inside the batch.
How many invoices can I merge at once?
Free batches 2 invoices per merge, once per day, with each file up to 2 MB and 50 pages. A typical weekly AP run exceeds that, so Pro — which removes the count cap and raises per-file limits to 50 MB / 500 pages — is the practical tier for recurring batching.
Can I add a sequential reference number for the audit trail?
Yes. After merging, run the batch through PDF Bates Numbering to stamp a unique sequential reference (e.g. AP-000001) on every page, or PDF Page Numbers for simple pagination. Numbering the merged batch keeps the reference continuous across all invoices.
A supplier's invoice is password-protected — can I still merge it?
Only if it doesn't require a password to open. The engine ignores permission-only restrictions (like print-blocking), so those merge fine, but a file that needs an open password can't be read. Remove the password first with PDF Remove Password for invoices you're authorised to handle, then merge.
Will the merged batch upload cleanly into Xero or QuickBooks?
Yes — the output is a single standard PDF that accounting platforms accept as one attachment. Merging is often used precisely to turn a stack of separate bills into one file for upload. The tool doesn't integrate with those platforms directly; it just produces the consolidated PDF you attach.
Are scanned paper invoices searchable after merging?
No. A scanned invoice is an image, and merging doesn't run OCR, so it stays unsearchable in the batch (digital/text invoices remain searchable). To make the merged AP file searchable by supplier name or amount, run PDF OCR on it afterward to add an invisible text layer.
Can I reorder invoices in the merge panel?
No — there's no drag-to-reorder; invoices merge in the order you add them. Load them grouped by supplier or sorted by date (a filename convention helps). To fix an order mistake, remove and re-add the file, or rearrange the merged batch with PDF Reorder.
What if an invoice is a fillable PDF form?
Flatten it first. Merging copies pages but doesn't preserve a working AcroForm, so entered values in a fillable invoice could be lost. Run it through PDF Flatten to convert the filled fields into permanent static content, then merge.
My scanned bills are too large for the free limit — what now?
Scanned paper invoices often exceed the 2 MB free per-file cap. Compress them first with PDF Compress (Aggressive) (you can target a size like 1 MB), then merge — the amounts stay readable, which is fine for archival AP records. Pro raises the per-file limit to 50 MB if you'd rather keep full quality.
Can I pull a single supplier's invoice back out of the batch?
Yes. Your originals are never modified, but if you only have the merged batch, use PDF Extract Pages to pull a page range into a new file, or PDF Split by Range to break the batch into per-supplier sections.
Privacy first
All PDF processing runs locally in your browser using PDF-lib and pdf.js. No file is ever uploaded — only metadata counters are saved for signed-in dashboard stats.