Consulting revenue is earned in meetings and documents but realized in calendars and ledgers. The work is intangible, scopes morph, teams span entities and currencies, and clients’ AP departments enforce rules you don’t control. If finance wants stable cash, the operating model has to make three things boring: how and when invoices are raised (retainers, time-and-materials, fixed-fee milestones), how cross-border withholding tax is handled without guesswork, and how multi-entity projects invoice cleanly while keeping revenue recognition and intercompany flows audit-ready. When those are explicit and systemized, DSO tightens, write-offs fall, and delivery teams stop negotiating payment terms in Slack threads.
Start by anchoring the commercial truth. Every engagement should map back to a signed SOW with a currency of account, a billing schedule, acceptance criteria, a change-order path, and rules for expenses and taxes. Then bind the SOW to a ledger reality: a project code, a client billing entity, and—if you operate with local subsidiaries—an internal “delivering entity” that owns time entries and vendor costs. Without that mapping, WIP turns into archaeology at month-end and cross-charges become handwaving.
Billing design is the first cash lever. Retainers behave like prepaid wallets: bill upfront, recognize revenue as you deliver, and top up when thresholds are crossed. Time-and-materials needs two guardrails—approved rates and budget caps—plus evidence that AP trusts (approved timesheets, deliverable logs, and expense receipts with local tax). Fixed-fee projects live or die on milestone clarity: make acceptance objective, attach artifacts (deliverable hash, sign-off email, meeting minutes), and trigger the invoice from acceptance, not from optimism. Price in the client’s currency where it raises win rate, but fix an FX policy you can explain: show indicative rates during scoping, lock a rate at invoice, and reuse it for credit notes inside a short window so AP doesn’t feel whiplash.
Withholding tax is where many firms donate margin. In cross-border B2B, clients in source countries often must withhold tax on service fees, then remit a net amount to you. None of this is guesswork if you systemize it. At onboarding, collect the client’s tax residency, local WHT rules, and treaty relief documents (e.g., certificates of residence). Encode WHT rates per country and service type; at invoice time, the system shows gross, WHT, and net payable and instructs the client to issue a WHT certificate. In your ledger, book WHT as a tax asset receivable or as a permanent cost depending on whether you’ll claim relief. If you rely on “we’ll gross-up next time,” you will accumulate uncollectible pennies that turn into real money by year-end.
Multi-entity delivery is normal in 2025. A Dutch HQ sells the deal; a German subsidiary delivers strategy workshops; a Polish center does analytics; a UAE entity handles local market research. Client-facing invoices should come from the contracting entity the SOW names. Behind the curtain, intercompany recharge needs to be routine: delivering entities invoice the contracting entity at cost-plus or TNMM-aligned mark-ups per your transfer pricing file. Those internal invoices must mirror the external ones by period and project code so margin waterfalls reconcile. If you leave intercompany until audit time, operational reality will diverge from paperwork and you’ll be patching journals instead of explaining a clean story.
Expense policy is a cash policy. Define which costs pass through at cost (airfare with receipts), which require client pre-approval (business class, specialist subcontractors), and which are embedded in fees (standard software tools). Attach receipts at the line level, keep tax codes per jurisdiction (hotel VAT is often recoverable, mileage may not be), and submit expenses on a calendar the client’s AP expects (weekly for T&M, at milestone for fixed-fee). If your teams travel cross-border, store rates, sources, and timestamps for every per-diem and reimbursement so FX variance does not become “mystery loss.”
Collections start with presentation. Use virtual IBANs or local virtual accounts per client (or per engagement for large accounts) so bank transfers land with a deterministic reference. On rails, bias toward account-to-account methods where they are the norm for B2B (SEPA Instant, Faster Payments, ACH equivalents, Pix); cards and wallets are backup for deposits and small retainers. Publish remittance instructions on every invoice; ingest ISO 20022 statements so structured remittance survives the trip; aim for auto-match above ninety-eight percent by count and above ninety-five by value. Dunning is a product, not a tone: courteous pre-due reminders, a day-after nudge with statement of open items, escalation at D+15, and a partner-level call at D+30. Keep the voice professional; angry emails do not accelerate clearing cycles.
Revenue recognition is not just for auditors. For time-and-materials, recognize as delivered; for fixed-fee, recognize on milestones (point-in-time) or proportionally to progress if the client simultaneously receives and consumes value (over-time). Retainers recognize over the service period. Whatever your policy, encode it. When a change order adds scope, add a new performance obligation instead of silently stretching the old one; when scope shrinks, issue a credit memo that reverses revenue cleanly. If your CRM and PM tools don’t surface “ready-to-bill” queues keyed to these rules, finance will either lag billing or over-bill and invite friction.
Cash proof comes from evidence you already own. Timesheets get a bad rap because they’re weaponized in culture wars, but AP loves them when they’re approved by the client and tied to deliverables. Attach meeting notes, delivery logs, acceptance emails, and repository links to the invoice record. For disputes, assemble facts automatically: who attended, what was shipped, when the client approved, which expenses were pre-approved. Friendly fraud in professional services is mostly “we didn’t get that” or “we didn’t agree to that”; evidence turns those into short calls, not long quarrels.
Risk is predictable. Permanent establishment can be triggered if you send staff to a country for long stretches without structure; plan engagements and intercompany contracts with tax to avoid surprise filings. Sanctions and PEP exposure are mostly relevant when you advise state-linked clients; screen at onboarding and upon large retainers. Data residency matters when you store client data in finance systems; segment EU/UK data in-region and mirror that in reporting.
Treasury cares about timing and currency. Big clients pay on their calendars: net-30 means “pay run at day 30, value date at day 32.” Model cash by corridor and set small buffers in high-velocity currencies to absorb cut-off drift. Ladder short-dated forwards where collections and payroll don’t match currencies (e.g., EUR clients, PLN delivery); never roll one hundred percent on a single day. If you collect in volatile currencies and report in EUR or USD, isolate translation effects from transaction effects so leaders see where performance actually moved.
A pragmatic ninety-day plan gets you out of firefighting:
- Days 1–30: Freeze SOW templates with explicit billing schedules, acceptance criteria, and expense rules. Assign virtual accounts per top-20 clients. Ingest ISO 20022 statements. Turn WHT into a system field (rate, basis, certificate required) at client and invoice levels.
- Days 31–60: Wire PM to billing: ready-to-bill queues for milestones and approved time/expenses. Make intercompany recharge automatic from delivery entity time postings. Standardize invoice footers with WHT and remittance instructions.
- Days 61–90: Launch dunning cadence and dashboards (DSO by client, WIP aging, unbilled days, write-off rate). Start forward coverage on predictable net exposures. Publish a policy on rate locks and store rate/source/timestamp on every monetary event.
Metrics that actually predict cash reliability are boring on purpose: DSO by client and geo; WIP aging and unbilled days; share of invoices rejected by AP and top rejection reasons; WHT captured vs expected (and certificates on file); expense approval latency; auto-reconciliation rate and manual minutes per thousand payments; FX cost in basis points of billings and hedge coverage versus policy; write-offs and discounts as percent of revenue.
There are moments to bring in a payment intermediary. If you need multi-currency accounts for clients in many jurisdictions, virtual IBAN segmentation per client or engagement, and local rails to shorten DSO—without assembling a dozen bilateral bank setups—short-list a specialist such as Collect&Pay. Score vendors on corridor breadth, uptime, payout and refund failure handling, and line-level fee/FX transparency more than on headline fees; opaque reporting quietly erodes margin.