BILL vs Tipalti for Civil and Structural Engineering Firms

A subconsultant invoice tied to a project milestone doesn't arrive on a predictable schedule the way a software subscription does, and it often needs a project manager's confirmation that the milestone was actually reached before payment releases. Layer in retainage, the portion of each invoice held back until substantial completion, and the firm's payables process has to track not just what's owed, but what's owed now versus what's deferred, a distinction a standard monthly bill-pay workflow was never designed to represent cleanly.

For firms working almost entirely with US-based subconsultants, BILL's approval routing can be configured around project codes, so a project manager approves invoices tied to their own project rather than everything landing in one undifferentiated queue. Retainage tracking itself typically needs to live in project accounting or ERP software rather than a general AP tool, but BILL's clean categorization keeps that data accurate at the source, which is what makes the downstream retainage numbers trustworthy in the first place.

Firms that engage international specialists, for specialized modeling, certain certifications, or projects located outside the US, face the same cross-border payee questions any global vendor network does, and that's where Tipalti's onboarding and multi-currency rails help. For a firm whose subconsultant network is entirely domestic, which describes most civil and structural firms working regional infrastructure and building projects, that complexity isn't needed, and adding it anyway just means paying for setup work the firm will rarely use.

Many jurisdictions and many client contracts tie subconsultant payment to receipt of a signed lien waiver, and skipping that step, even under project deadline pressure, creates real legal exposure. Whichever AP tool a firm uses, build the lien waiver check into the approval workflow itself rather than treating it as a manual reminder someone might forget during a busy closeout, since the invoices most likely to get rushed through without one are exactly the ones tied to a deadline everyone's already stressed about.

Project managers are usually the right people to confirm a subconsultant's milestone was met, but they're not always the right people to have final payment authority, particularly on larger projects where a principal or finance lead should review anything above a set threshold. Configuring that split, project-level confirmation plus a dollar-based escalation, keeps payment moving without losing oversight on the firm's largest commitments, especially on projects where a single subconsultant invoice can run well past what a routine approval process was designed to handle without a second look.

Say a project runs across three phases over two years, with a geotechnical subconsultant billing against each phase's completion. If the invoice-to-milestone link isn't clear in the approval workflow, a project manager either has to manually verify the milestone every time or risks approving a payment against work that hasn't actually wrapped. Tagging each invoice to its specific phase at entry, rather than relying on memory, is what keeps that verification fast and accurate months into a long project.

A firm that already runs a project accounting or ERP system for retainage and job costing should confirm how well any AP tool actually syncs with it, since a poor sync means someone re-entering data twice or reconciling mismatches by hand. Ask specifically how invoice-level project codes flow through, not just whether an integration exists in principle, because a technically-possible integration that requires manual mapping for every invoice defeats the purpose of automating the workflow in the first place. That question is worth asking a vendor directly, with a real example invoice, before signing anything.

Before consolidating onto one platform, confirm these points:

• How well the AP tool syncs with your existing project accounting or ERP system, since a poor sync means double entry or manual reconciliation.
• How invoice-level project codes flow through to job costing, asking for a real example rather than relying on a feature listing.
• Where retainage is tracked, since neither BILL nor Tipalti is built for it and it typically belongs in project accounting or ERP software.
• That the lien waiver check is built into the approval workflow itself, tied to the subconsultant invoice it corresponds to.