Vendor Onboarding Checklist to Get Paid Faster

If you’ve ever heard, “We’re processing it,” and then waited three more weeks, you already know the truth:

Late payments are often not about trust, quality, or you being “too nice”. They’re about process.

Your invoice can be perfectly valid, and still sit unpaid because:

1. it went to the wrong person,
2. the client needs a PO number,
3. you are not set up as a vendor in their system,
4. Accounts Payable (AP) needs tax or banking details,
5. or procurement requires a vendor ID before they can approve anything.

This guide is built to fix that.

You’ll get a vendor onboarding checklist you can copy/paste, a “minimum viable vendor packet” you can keep ready, plus scripts that remove delays without sounding pushy.

Key takeaways

1. Vendor onboarding is payment readiness, not paperwork for fun, it decides whether your invoices can be approved and paid.
2. The fastest path is to confirm the billing route on day one (AP contact, PO rules, vendor portal, pay run schedule).
3. Most delays come from five preventable issues: wrong recipient, missing PO, legal name mismatch, incomplete bank info, and unclear invoice requirements.
4. A “minimum viable vendor packet” saves days of back-and-forth and makes you look enterprise-ready.
5. Once you are onboarded, a predictable reminder cadence beats awkward chasing, and you can automate it with automatic invoice reminders.

What vendor onboarding is (and why it affects your cash flow)

Vendor onboarding is the process a client uses to gather the information and approvals they need to set you up as a payable supplier. In plain language, it is the “create you in the system so AP can pay you” step.

For freelancers and agencies, vendor onboarding is the hidden gatekeeper:

1. No vendor record, no vendor ID, no payment.
2. No PO number, no invoice approval.
3. No correct legal entity, payment gets stuck in “verification.”

If you want the full “systems view” of why clients pay late (and how to fix it upstream), pair this article with how to reduce late payments from clients.

The “Get Paid Faster” vendor onboarding framework

Think of vendor onboarding as five boxes. If any box is missing, payment slows down.

1. Route: Who receives invoices (AP email, portal, person)?
2. Identity: Who are you legally (name, address, tax status)?
3. Payment: How can they pay you (bank details, method, remittance)?
4. Approval: What internal references do they need (PO, cost center, vendor ID)?
5. Follow-up: How will you nudge without friction (cadence + templates + stop-when-paid)?

The checklist below walks through those boxes in order.

Vendor onboarding checklist (copy/paste)

Use this as a Notion page, a Google Doc, or a recurring task template. The goal is not perfection, the goal is to eliminate payment blockers before they exist.

1) Confirm the billing path (before you start)

Ask these questions at kickoff, not after the invoice is overdue:

1. Where should invoices be sent? (email and name)
2. Should someone be CC’d? (project owner, finance lead)
3. Do you require a vendor setup step before invoicing?
4. Do you require a PO number? If yes:
5. Who issues it?
6. Do you need it on the invoice subject line, invoice header, or line items?
7. Do you use a vendor portal? (Coupa, Ariba, Tipalti, Bill.com, custom portal)
8. What’s your pay run schedule? (weekly, twice monthly, monthly)
9. What’s your standard payment term? (Net 7/14/30/45/60)

Why this matters: it turns “we will pay soon” into an actual internal workflow you can align with.

If you want a broader process lens (AR cadence, KPIs, and a small-business workflow), this pairs well with accounts receivable best practices.

Copy/paste micro-email (billing route):

Subject: Quick billing setup so invoicing is smooth

Hi [Name], quick check so we keep billing friction-free:

1. What email should invoices go to (and should anyone be CC’d)?
2. Do you require a PO number or vendor setup before invoices can be processed?
3. What is your typical pay run schedule (weekly, twice monthly, monthly)?

Thanks,

[Your Name]

2) Collect the minimum vendor profile

Create a single “source of truth” record for each client. This prevents mismatches when they enter you into AP.

Minimum vendor profile fields:

1. Legal business name (exact)
2. DBA / trading name (if different)
3. Country of registration
4. Registered address
5. Primary contact name, email, phone
6. Billing contact (AP) name and email (if different)
7. Tax identification (depends on country)
8. VAT ID (if applicable)
9. Preferred payment method (bank transfer, card, ACH, etc.)

Pro tip: if you are a freelancer working under your personal name in some contexts and a company name in others, pick one and be consistent per client. “Close enough” triggers review.

3) Prepare tax and business identity documents

Different clients require different documents, often based on where they are located and how their finance team handles compliance.

Common examples:

1. US clients often request Form W-9 (to request your taxpayer identification number).
2. If you are not a US person, clients may request a W-8 series form (for example W-8BEN for individuals).
3. EU clients may request your VAT identification number and may validate it.

Important: this article is operational guidance, not legal or tax advice. If you are unsure which tax form applies, ask your accountant or the client’s finance team what they require.

Checklist: identity and tax docs

1. Business registration certificate (if applicable)
2. Tax form requested by the client (W-9 or W-8 series where relevant)
3. VAT ID (if applicable) and legal name match
4. A short “vendor info sheet” (we’ll build this below)

4) Prepare payment details (securely)

This is where many vendors lose time, because AP teams often require verification.

Typical fields clients request:

1. Account holder name (must match legal name)
2. Bank name and bank address (sometimes optional)
3. IBAN + SWIFT/BIC (common for international transfers)
4. Routing + account number (common in the US)
5. Payment reference instructions (what they should include so you can reconcile)

Security rule: treat bank details as sensitive operational data.

1. Prefer secure portals or encrypted file sharing when possible.
2. Avoid sending full banking details repeatedly in long email threads.
3. If the client insists on email, send once, then refer to the same document.

5) Confirm PO requirements and invoicing rules (this prevents “unpayable invoices”)

A surprising number of “late payments” are actually “unapprovable invoices”.

Ask these questions:

1. Do invoices require a PO number to be paid?
2. Does the PO need to be created before work starts, before invoicing, or per month (retainers)?
3. Where must the PO appear on the invoice?
4. Do you require a vendor ID on invoices?
5. Do you require line item structure, specific description formats, or cost center codes?
6. Do you require invoice submission through a portal only?

Why PO matters: in many organizations, the PO number is how they match your invoice to an approved budget. If the PO is missing, your invoice can stall even if everyone likes you.

If you run an agency: billing structure often reduces PO pain.

1. Retainers can be “rent-like” and align with monthly pay runs.
2. Milestones turn big scary invoices into smaller approvals.

If you want a practical breakdown (with terms you can copy), see billing models that get agencies paid faster.

6) Submit the vendor packet and get a vendor ID

Your goal is a clear confirmation like:

1. “You are set up as Vendor #12345”
2. “You are active in the portal”
3. “Invoices can now be processed”

Checklist:

1. Submit vendor onboarding form (their template)
2. Attach requested tax form and vendor info sheet
3. Confirm invoice delivery method (email vs portal)
4. Ask for vendor ID and pay run schedule
5. Save the confirmation in your client record

Copy/paste email (submit packet):

Subject: Vendor setup details (for invoicing and payment)

Hi [Name], as requested, here are our vendor onboarding details:

1. Legal name: [Legal Name]
2. Address: [Address]
3. Tax/VAT: [ID]
4. Payment method: [Bank transfer / ACH / etc.]
5. Invoicing email/portal: [Confirm what they want]

Attached: [Vendor info sheet] + [requested tax form].

Could you confirm once we are set up in your system (vendor ID if applicable) and the next pay run date?

Thanks,

[Your Name]

7) Invoice in the exact format they accept

Before you send the first invoice, do a 60-second “invoice acceptance” check:

1. Correct legal name and address (match onboarding)
2. Correct recipient (AP email or portal)
3. PO number included (if required)
4. Due date and payment terms shown clearly
5. Payment instructions included (or payment link)
6. Invoice number present and referenced in email subject

If you want copy for different timings (7 days before, due date, overdue), use these invoice reminder email templates.

8) Follow up with a predictable cadence (not vibes)

After you are correctly onboarded, the best collections strategy is boring consistency.

Baseline cadence that works for many service businesses:

1. 7 days before due date (friendly heads-up, for Net 15/Net 30)
2. Due date (neutral reminder)
3. 3 days overdue (assume oversight, ask for status)
4. 7 days overdue (ask for a payment date, remove blockers)
5. 14 days overdue (final step, policy-based)

For a timing playbook by payment terms and invoice size, use the best invoice reminder schedule.

If you want the exact dates generated from your invoice due date (with ready-to-use copy), use the invoice reminder schedule builder.

The “Minimum Viable Vendor Packet” (MVVP)

If you work with multiple clients, keep one packet updated and reuse it.

What your MVVP includes

1. One-page vendor info sheet (PDF)
2. Any tax form commonly requested by your client base (or ready to generate quickly)
3. Bank details document (securely shared)
4. A short note: “Invoice submission method” (email/portal) and “required references” (PO/vendor ID)

One-page vendor info sheet template (copy/paste)

Vendor Information Sheet

1. Legal business name:
2. DBA (if any):
3. Registration country:
4. Registered address:
5. Primary contact:
6. Email:
7. Phone:

Billing and payment

1. Preferred currency:
2. Preferred payment method:
3. Bank name:
4. Account holder name:
5. IBAN:
6. SWIFT/BIC:
7. Routing number (if applicable):
8. Account number (if applicable):
9. Payment reference instructions: “Please include invoice number in the transfer reference.”

Tax

1. Tax ID / TIN:
2. VAT ID (if applicable):
3. Tax form provided (if requested by client):

Invoice requirements (client-specific, fill after onboarding)

1. Invoice submission: (Email or portal)
2. AP email:
3. PO required: (Yes/No)
4. Vendor ID required: (Yes/No)
5. Pay run: (weekly / twice monthly / monthly)

This document does two things: it speeds up onboarding, and it prevents mismatches later.

Email scripts to speed up vendor setup (copy/paste)

If you only take one thing from this article, take these scripts. They turn vague payment situations into clear operational steps.

Script 1: “Who should invoices go to?”

Subject: Confirming invoicing contact

Hi [Name], quick one so invoicing stays smooth.

Who should receive invoices (AP email), and should anyone be CC’d?

Thanks,

[Your Name]

Script 2: “Do you need PO or vendor setup?”

Subject: Billing requirements check

Hi [Name], before we start, do you require a PO number or vendor setup for invoices to be approved and paid?

If yes, happy to send whatever your team needs.

Thanks,

[Your Name]

Script 3: “Here’s what I need from you to avoid delays”

Subject: To avoid payment delays, can you confirm these?

Hi [Name], to keep billing friction-free, can you confirm:

1. Invoice submission method (email or portal)
2. Any required references (PO, cost center, vendor ID)
3. Typical pay run schedule

Thanks,

[Your Name]

Script 4: “Second notice that stays professional”

When you are in the awkward middle, do not improvise. Use a proven template like the second notice overdue invoice email template and keep it factual.

If you want to generate the same tone in seconds for different scenarios (friendly, professional, firm), use the invoice reminder email generator.

Common blockers (and the fastest fixes)

Blocker 1: “We didn’t receive the invoice”

Fix:

1. resend the invoice link or attach PDF
2. confirm correct AP recipient
3. ask for “preferred invoice submission method”

Blocker 2: “We need a PO number”

Fix:

1. ask who issues the PO and expected timing
2. pause sending new invoices until PO process is clear
3. align your billing model (retainer or milestones) to reduce PO churn

(PO matching is a common approval control, and missing PO can stall payment even if work is complete.)

Blocker 3: Legal name mismatch

Fix:

1. use the exact legal name from onboarding on every invoice
2. keep a single “vendor info sheet” to avoid drift

Blocker 4: Bank detail verification takes forever

Fix:

1. provide a single official banking document (one source of truth)
2. share securely
3. ask AP what verification they require (sometimes a letter or proof)

Blocker 5: Portal-only invoicing

Fix:

1. ask for portal access early
2. confirm whether reminders can be sent outside the portal (often yes)
3. keep a manual reminder cadence that points back to the portal invoice reference

After onboarding, stop chasing with a system

Vendor onboarding gets you into the payment system. It does not guarantee you get paid on time.

That’s where process wins.

Step 1: Standardize cadence and templates

Start with:

1. timing: when to send invoice reminders
2. copy: invoice reminder email templates

Step 2: Turn “cadence” into exact dates

A cadence is advice. A schedule is execution.

Use the invoice reminder schedule builder to generate exact send dates and ready-to-use emails based on your due date and payment terms.

Step 3: Automate follow-ups so you are consistent

If your reminders depend on memory, they will fail exactly when you are busiest.

Read how automatic invoice reminders work, then decide what you want automated first (pre-due, due-date, overdue, or all of it).

If you are comparing options, this guide to invoice reminder software for small business explains when built-in reminders are enough and when dedicated follow-ups are the better workflow.

A simple tool stack for faster payments

You do not need a complicated finance stack. You need fewer unpaid invoices.

A minimal stack:

1. Vendor packet (MVVP) stored and ready
2. A clear billing route (AP email, portal, PO rules)
3. A reminder cadence with templates
4. Automation so follow-ups happen consistently

If you want the shortest path from “I should do this” to “it’s done”, start with the free tools:

1. invoice reminder schedule builder
2. invoice reminder email generator

Then, when you are ready to stop chasing entirely, check the product at https://canyoupaythat.com.

Conclusion

Getting paid faster is rarely about sending tougher emails.

It’s about removing the reasons invoices become unpayable:

1. vendor not set up,
2. PO missing,
3. invoice format wrong,
4. wrong recipient,
5. bank details unclear,
6. reminders inconsistent.

Use the checklist, keep a minimum viable vendor packet ready, and run a predictable follow-up cadence. Once it works manually, automate it so it runs even when you are busy.

Next step: Generate a schedule and copy today with the invoice reminder schedule builder, then check Can You Pay That when you want it fully automatic.

FAQ

1) What documents are typically required for vendor onboarding?

Usually a vendor onboarding form plus identity and payment details. Depending on the client, you may also need tax forms, VAT ID, and proof of banking instructions.

2) How long does vendor onboarding take?

It can be same-day for small clients, and 1–4+ weeks for larger organizations with procurement review and portal setup.

3) Do I need a W-9 or W-8 form?

US clients commonly request W-9 to collect taxpayer information. If you are not a US person, clients may request a W-8 series form (for example W-8BEN).

4) What is a PO number and why does it block payment?

A PO number is an internal approval reference used to match invoices to budgeted purchases. If it’s required and missing, invoices often cannot be approved for payment.

5) Should I email bank details to Accounts Payable?

Prefer a secure portal or a single PDF document shared once, then referenced. Avoid repeating bank details in long email threads.

6) What do I do if the client requires a vendor portal?

Ask for portal access during kickoff, confirm submission rules (format, required fields), and save your vendor ID and invoice references.

7) Who should receive invoice reminders, buyer or AP?

For small clients, the buyer often pays. For larger clients, AP should receive invoices, and the buyer can be CC’d for visibility.

8) What is the fastest follow-up cadence after an invoice is sent?

A common baseline is 7 days before due date, due date, then 3/7/14 days overdue, escalating calmly and stopping when paid.