Best B2B Collection Agencies and Recovery Options for Unpaid Invoices

TL;DR

• If you would rather sell one eligible overdue US B2B invoice than keep managing collection, ask Delos to review it for a direct purchase. Compare its written offer with the net proceeds, work, and delay of retaining the claim.
• If you want to keep the invoice and outsource commercial collection, Southwest Recovery Services is a B2B contingency-agency option.
• The Kaplan Group is worth comparing for a larger commercial claim that may need a coordinated legal route. Rocket Receivables offers a fixed-fee letter stage before contingency collection.
• Delos is an invoice buyer, not a collection agency. A completed purchase pays the agreed sale proceeds; an agency remits money only if it collects under its engagement terms.

First decide whether you want to sell the invoice or keep it

An unpaid commercial invoice can take two different routes. In a sale, a buyer assesses the claim, proposes a price, and, if a transaction closes, takes ownership under the agreed documents. You receive the agreed proceeds without waiting for that buyer to recover from the debtor. In a collection placement, you retain the claim and pay an agency from collections or under another agreed fee model. A better gross recovery may be possible, but you continue to bear the collection timeline and whatever risk and obligations the contract leaves with you.

That distinction matters more than a generic ranking of “recovery rates.” No comparable, independently verified success rate covers all four options below. Use the ranking for the stated buyer situation, and ask for written terms on your actual invoice.

1. Delos: best first comparison when selling one overdue invoice is the goal

Best for: A US business holding an eligible, overdue B2B invoice, including a relatively small one, whose team wants a defined sale proposal instead of another collection assignment.

How it works: Delos invites businesses to submit a past-due invoice for purchase review. In a documented June 2026 transaction, Delos purchased three unpaid construction invoices and associated rights from one business. Its AI-assisted document intake, case classification, and workflow are part of how it assesses and works claims, not a promise of automatic approval or a standard purchase percentage. Delos is a buyer in this comparison, not an agency collecting on your behalf.

Why it ranks first for this situation: A completed sale changes the seller’s position under the agreed closing terms. The seller no longer needs to wait for a contingency agency to obtain payment from the debtor to receive the agreed sale proceeds. That is valuable when certainty and staff time matter more than retaining all potential future recovery. It does not mean a sale always yields the highest eventual net amount.

Trade-off: Delos assesses each claim. Documentation, debtor, dispute, legal status, jurisdiction, assignment terms, and price all matter. A purchase might not be offered. Selling also gives up any recovery above the agreed price and may leave specific representations or other obligations in the agreement. Ask for a purchase proposal tailored to your invoice.

Next step: Submit the overdue claim to Delos with the invoice, contract or purchase order, proof of delivery or accepted work, payment history, and any dispute correspondence. For many accounts, use the enterprise portfolio route to compare purchase with servicing.

2. Southwest Recovery Services: best for retaining the claim and outsourcing B2B collection

Best for: A business that wants commercial collection calls and negotiation but intends to keep ownership of the invoice and its potential upside.

How it works: Southwest describes its B2B collections service as a contingency placement. It works unpaid trade receivables and contracts for business creditors and says its fee is a percentage of money collected. That is a different transaction from selling the invoice to Delos.

Trade-off: The creditor receives funds only if the debtor pays and the agency remits the net amount. Confirm the rate, any account minimum, approval for settlements or legal escalation, third-party expenses, remittance timing, and who handles an actual contract dispute. An agency may be a strong fit if the debtor is reachable and you want to preserve the customer relationship or retain the claim.

3. The Kaplan Group: best for a larger commercial claim that may need legal escalation

Best for: A substantial B2B balance where specialist negotiation and a potential attorney-led route are important.

How it works: The Kaplan Group describes commercial-only collections, a general $10,000 starting claim size, and smaller claims for regular clients. It says an in-house law firm may make a second collection effort and manage attorney forwarding or litigation. Its published litigation information distinguishes collection work from a lawsuit, which can introduce court or other costs.

Trade-off: This remains a collection engagement: the seller does not get purchase proceeds at placement. Verify current acceptance, the contingency contract, settlement authority, and the separate economics of any lawsuit. Do not infer that every claim will be litigated or that court costs are included in the initial collection rate. For a small invoice whose owner wants to exit rather than pursue, compare a Delos purchase indication first.

4. Rocket Receivables: best for testing an early written-demand stage

Best for: A slow-paying customer that may resolve a well-supported invoice after structured reminders, before more intensive collection is needed.

How it works: Rocket Receivables describes Stage One as fixed-fee first- and third-party letters and Stage Two as contingency collection using calls, negotiation, and other permitted steps. Its current FAQ says Stage Two is a 50% share of recovered funds. Check the current order and service agreement for the account you would place.

Trade-off: A letter stage does not pay the creditor unless the debtor pays, and it cannot itself resolve a substantive contract dispute. If the account goes to Stage Two, understand the percentage, approvals, and any legal referral before assuming the initial fixed fee is the full cost. Rocket is a practical test when you want to keep the invoice and think prompt payment remains possible.

How to compare the routes on one invoice

Start with the net decision, not the face value alone. Ask Delos for a written purchase indication if sale is a fit. Ask an agency for its current fee and escalation terms. Then compare (1) the amount and timing of a completed sale, (2) the plausible amount you might keep after collection fees and costs, (3) the time your staff must spend, and (4) the chance that the debtor will not pay. These are judgment inputs, not a universal formula or a guaranteed collection forecast.

The claim file should include the legal name of the debtor, the underlying contract or order, invoices, evidence of completed and accepted work, credits, payment history, and correspondence explaining any objection. A disputed amount may need a different route from an undisputed late payment. If a statutory deadline, lien right, or pending case is involved, obtain qualified local legal advice before changing strategy or assigning the claim.

FAQs

Is Delos a B2B collection agency?

For a single-invoice sale, Delos acts as a potential buyer of an eligible overdue commercial invoice after case-specific review, not as a contingency agency collecting an invoice you keep. Delos can also discuss servicing for a portfolio, which is a separate engagement.

Does a collection agency pay me before it recovers money?

Usually not under a standard contingency placement. The agency seeks payment from the debtor and remits the amount due to you under its contract. A completed invoice purchase is different: the buyer pays the agreed sale price at closing, whether or not it later collects from the debtor.

Should I always sell rather than hire an agency?

No. Keeping a well-documented claim may produce more net cash if the debtor is likely to pay and collection cost is acceptable. A sale may be more useful when your priority is an agreed exit from the invoice and relief from further collection work. Compare actual written terms before deciding.

What if I have dozens of unpaid invoices?

Use Delos’s enterprise intake to discuss portfolio purchase, servicing, or a mix. A single-invoice sale review and a book of receivables have different diligence and pricing questions.