Professional Services Automation Software Billing Compared (2026)

The billing problem, not the project management problem

All five of these platforms get marketed as project management or resource planning software, but the reason a professional services firm actually buys one is usually billing. A consultant logs eight hours against a client engagement. That time sits as unbilled work in progress, WIP, until someone converts it into an invoice, and the firm has done the work without collecting the cash for it until that invoice is issued and paid. A firm that lets WIP age for three or four weeks because nobody ran the report can show a healthy month on the income statement and still come up short at payroll. Retainer clients add a second layer: a monthly fee tied to a bucket of hours that someone has to track against actual usage, then bill the overage, or explain the shortfall, before the client questions the invoice. Certinia, Kantata, Accelo, Scoro, and Productive all claim to solve this, but they solve it differently and at very different price points, and most vendor comparison pages ranking them side by side never test the one feature that actually decides whether you get paid on time: how cleanly logged time turns into an invoice a client will not dispute.

What each platform actually costs (verified 2026-08-30)

Two of these numbers are worth flagging specifically because most comparison sites still get them wrong. Scoro rebuilt its pricing around modular apps in 2026, replacing the old Essential, Standard, Pro, and Ultimate tiers that several sites ranking for "scoro pricing" still describe; the current model lets you buy just the billing pieces (Track plus Invoice) instead of the whole platform. Accelo went further and pulled published starting prices off its own site entirely, so the "$30/user/month" figure that shows up on several aggregator pages no longer matches what Accelo's own pricing page shows. Certinia and Kantata have never published list pricing, so the ranges above come from third-party deal benchmarking rather than a vendor rate card, and both will want a discovery call before quoting your specific seat count.

How billing and WIP actually work on each platform

Certinia runs its billing engine natively inside the Salesforce object model: project milestones, time cards, and expense reports roll up through Salesforce's own invoicing objects rather than a separate billing database. That is the strongest argument for it if your firm already runs Salesforce as CRM and financial system of record, since there is no second system to reconcile against. It is also the weakest argument for everyone else, because you are paying for a Salesforce license on top of Certinia, and aggregated buyer feedback across independent sources (SelectHub and buyer-review aggregator QuickPayable, both checked 2026-08-30) consistently puts implementation with a certified partner at three to nine months.

Kantata's reviewers describe the core billing flow, time entry, marking a milestone complete, allocating a purchase order, and generating the invoice, as quick and trackable once set up. The documented weak spot sits one step later: the expense and invoicing tool works in a single currency at a time, which becomes a real problem for firms with international clients or contractors paid in a currency other than the one the project was quoted in. Aggregated Capterra and G2 feedback also flags weak native integration with accounting platforms, meaning invoices generated in Kantata often need manual reconciliation once they land in QuickBooks, Xero, or NetSuite.

Accelo builds retainer billing as a first-class feature rather than a workaround: recurring service contracts carry usage caps, automatic monthly billing, and client notifications when a retainer's hour budget approaches its limit, all inside the same record used for CRM and helpdesk. That means a client conversation about scope creep and the invoice for the overage live in one place instead of two systems that need to agree with each other. The tradeoff is a UI that one G2 reviewer described bluntly as "about 10 years out of date," and Accelo's own marketing claims of 3 to 7 percent revenue-leakage recovery and 30 to 35 percent lower admin overhead are the vendor's own figures, not an independently audited benchmark, so treat that specific range as a sales claim rather than a verified finding.

Scoro's Invoice app converts logged time directly into a client invoice, and pairing it with Track, the time and labor cost app, is exactly the combination Scoro sells as its cheapest tier. That lets a firm buy only the WIP-to-invoice piece without paying for CRM, resource planning, or advanced financials modules it does not need yet, then add Resource and Deliver later if capacity planning becomes the actual bottleneck. Some reviewers describe Scoro's accounting-specific capabilities as thin compared to a dedicated finance system, and the 5-user minimum applies to every combination, so a two-person consultancy still pays for five seats.

Productive ships a WIP Analysis report inside its Financial Reporting Suite, alongside Project P&L and Campaign P&L, built specifically for agencies that need to see unbilled work before it goes stale. At $10 per user per month billed yearly, it is the most accessible full entry point in this group. Its G2 profile carries a fraction of the review volume of Kantata or Certinia (75 reviews versus 674 to 1,572), so buyers who lean on a large peer-review sample as part of due diligence will find much less to work with here, and some reviewers separately describe its broader reporting as less flexible than a dedicated BI tool despite the purpose-built WIP report.

Who this actually fits

Already running Salesforce as your CRM and financial system of record, with a services team large enough to absorb a multi-month rollout: Certinia keeps billing inside the platform you already trust, at the cost of an additional license and the longest implementation timeline of the five.

Selling retainer-based work, where the client relationship depends on transparent burn-rate reporting rather than a single invoice at the end of a project: Accelo's retainer engine is the most purpose-built of the group, but budget time for a sales call at every pricing tier and a genuine learning curve before your team is billing confidently.

Running multi-million-dollar, multi-year engagements with dedicated project accountants who already tolerate some manual reconciliation: Kantata's billing workflow is well-liked once configured, but plan around its single-currency limitation if any client or contractor gets paid in a different currency than the one the project was quoted in.

Testing whether billing automation is worth the switch before committing to a full PSA: Scoro's modular pricing is the only one of the five that lets you buy just the time-to-invoice piece for $17 per user per month and expand later, though the 5-user floor means very small teams pay for headcount they do not have.

Wanting the lowest-cost full platform and a WIP report built for agency billing specifically, without needing a large base of peer reviews to lean on: Productive fits, provided you are comfortable being an earlier adopter relative to the other four.

None of these decisions turn on which platform has the highest star rating; all five sit in the same 4.2-to-4.6 band on G2. They turn on whether your firm bills hourly, retainer, or milestone work, whether you already run Salesforce, and whether international currency support is a requirement or an edge case. For a narrower comparison of how subscription-style recurring billing tools handle the same conversion-to-cash problem outside professional services, see our Stripe vs. Chargebee vs. Recurly comparison; for the collections side of the same cash flow question once an invoice has gone out unpaid, see our accounts receivable collections software guide and our invoice-to-cash software comparison.

Frequently asked questions

Q: What does WIP mean in professional services billing?

Work in progress, or WIP, is time and expenses a firm has logged against a client project but has not yet invoiced. It shows up in project-tracking reports, not on the firm's bank statement, which is why a firm can look profitable on paper while still running short on cash if WIP is allowed to age instead of being converted into invoices on a regular cycle.

Q: Which of these platforms is cheapest for a small consulting firm just starting to formalize billing?

Scoro and Productive have the lowest verified entry points ($17/user/month for Scoro's Track-plus-Invoice combo, $10/user/month for Productive's Essential tier), and both let you buy billing automation without committing to the full platform on day one. Certinia, Kantata, and Accelo are all quote-based with no published starting price, which typically means a higher minimum spend aimed at larger teams.

Q: Does any of these five require Salesforce?

Only Certinia. It is built as a native Salesforce application, which means the cost of a Salesforce license sits on top of whatever Certinia itself charges. Kantata, Accelo, Scoro, and Productive are all standalone platforms that do not require a separate CRM purchase to function.

Q: Which platform handles retainer billing with usage tracking best?

Accelo, based on its own product design and G2 reviewer feedback, builds retainer management as a core feature: usage caps, automatic recurring billing, and client-facing notifications when a retainer's budget nears its limit. Scoro and Productive both support recurring and retainer-style invoicing but do not describe the same level of built-in burn-rate alerting in their own product documentation.

Q: Can any of these bill clients or pay contractors in multiple currencies?

Certinia, Accelo, Scoro, and Productive all support multi-currency invoicing at some level, though the depth varies by plan. Kantata is the one platform in this group with a documented limitation here: aggregated reviewer feedback describes its expense and invoicing tool as working in a single currency at a time, which is worth testing directly against your specific billing scenario before committing if you have international clients or a distributed contractor base.

Q: How reliable are the G2 review counts in the comparison table above?

The ratings and review counts in this article were pulled directly from each product's live G2 page on 2026-08-30, not from a third-party aggregator summarizing G2 data, since aggregator numbers for at least two of these platforms were found to be stale by the time we checked (Accelo's review count in particular was cited inconsistently across secondary sources). Review counts change continuously, so treat the figures here as a snapshot rather than a permanent number.