Net-15 clients still ask for one PDF so accounting can drop invoice and timesheet into the same AP folder. I used to export both tools, then paste them into whichever combiner ranked first. One Friday the timesheet footer still showed a client code and ticket titles from a different engagement. Rates, hours, and project names are enough for a bored third party to learn more than they should.
That was the day month-end stopped being a search-bar habit.
I finish the timesheet, then generate the invoice from those hours. Merging first and adjusting later ships a pack that disagrees with itself. For retainers with a flat fee I still export a period timesheet; AP teams ask for backup months later during audit season, and I refuse to rebuild under pressure.
If three invoices leave on the same Friday, I finish one folder completely before opening the next: merge, rename, attach, archive — then switch. Context-switching mid-combine is how Acme's timesheet lands under Beta's invoice number. The folder name and the merged filename must share the same invoice number string before I touch compose.
Example shape: inv-1042-acme-2026-08/ with 01-invoice-1042.pdf and 02-timesheet-2026-08.pdf. Filename discipline beats final-final-v3.pdf at midnight.
I open both PDFs. Invoice hours times rate should equal the timesheet rollup within the contract's rounding. Fix the source export. Do not patch after a cloud merge you cannot reverse cleanly. Optional PO or change-order page goes in only if the client asked in writing; last month's invoice for context creates which-amount-do-we-pay tickets.
I stack invoice then timesheet with https://pdfmergefiles.com in the browser, download once, and send ACME-INV-1042-invoice-timesheet.pdf through the email or portal the contract names. The two source PDFs stay in the folder for the inevitable resend-just-the-timesheet reply. If a platform already stores the invoice, I still keep this month-end merge when they request hours by email — platforms are uneven about exporting time.
Freelance invoices often carry home address, tax fragments, and wire details. I treat random PDF websites as optional third parties I did not hire. Once per billing tool upgrade I open PDF properties; some exporters embed full legal name, software version, and laptop paths. That is usually fine for the client. It is less fine if the same file also vacationed on a public compress host because Gmail bounced. If I need metadata stripped, I choose that tool on purpose.
Match the period. Invoice first. Timesheet second. No other client's project names in the footer. No second upload to shrink a few megabytes after you already chose a careful path. Month-end is already enough; the PDF part can stay a short habit that does not give your rate sheet a tour of someone else's disk.
Some vendor portals demand invoice in one field and backup docs in another. Follow the portal. Local combining is for the common email/AP case where one attachment prevents hunting. If your accountant generates the pack from bookkeeping software, let that system be source of truth and skip improvising parallel PDFs.
Close the period in both tools. Rename with the invoice number. Check totals. Combine invoice then timesheet without parking rates on an anonymous host. Attach once. Keep sources. That Friday I almost mixed Acme and Beta taught me more than any feature comparison chart — the footer was the tell, and the fix was folder discipline plus a combine step that does not create tourist copies.