Which AI Subscription Should a CA Firm Actually Buy? A Procurement Guide
There are two different questions hiding behind "which AI should we use", and mixing them up is why firms stall.
The first is which model is better at which task — a professional judgement, and one we have written about separately in which AI model CAs should use for which task and ChatGPT vs Claude vs Perplexity vs Grok.
The second is what does the firm buy — how many seats, on which tier, at what annual cost, with what contract, recovered how. That is a procurement decision, and it is the one that actually has to be signed off. This post is about the second question only.
Start With Seats, Not Tools
The most common mistake is buying one subscription "to try it" on the managing partner's card, and then discovering eighteen months later that four people are sharing a login.
Shared logins are a bad idea for reasons that go beyond licence terms. You lose any ability to see who used what, conversation history mixes across engagements, and if a confidentiality question ever arises you have no way to answer it. For a profession where the file is the defence, that is an unforced error.
Work out seats first:
| Who | Needs a seat? |
|---|---|
| Partners and managers reviewing, drafting, researching | Yes — this is where the time is worth the most |
| Qualified staff on fieldwork | Yes, once there is a defined use case |
| Articles | Usually yes, and this is where firms are most surprised by the return |
| Admin and support | Rarely, unless there is document-heavy work |
A ten-person firm typically lands on six to eight seats, not one and not ten.
The Tier Ladder, and Why It Is Not About Features
Consumer, business/team, enterprise, and API tiers are usually presented as a features-and-limits ladder. For a CA firm the more important difference is contractual, and it is covered in detail in where your client's data actually goes. The short version:
- Consumer tier — an individual product. Historically several have used conversation content for model improvement unless the user turns it off. Fine for work that involves no client data.
- Business / team tier — per-seat, centrally administered, and typically the lowest tier at which you get a data processing agreement and administrative control over the account.
- Enterprise — adds procurement machinery, SSO, retention controls, and negotiated terms. Rarely justified below a certain size.
- API — pay-per-use rather than per-seat. Different economics entirely, and the right answer when the AI sits inside a workflow rather than in front of a person.
The practical rule: the moment client data is involved, you need a tier that comes with a contract. That threshold, not the feature list, is what should drive the tier decision.
The Cost Question, Honestly
Per-seat pricing for business tiers of the major assistants clusters in a similar band, and it moves often enough that printing a table here would be wrong within a quarter. What does not move is the shape of the arithmetic, so do it with today's number:
Annual cost = seats × monthly price × 12 ( × exchange rate, if billed in USD )
For a firm of ten taking seven seats, this generally lands in the low lakhs per year. Set against it:
- What one seat replaces. Not headcount — hours. If a seat saves a manager three hours a month on drafting and research, at that firm's realisation rate, most firms find the seat pays for itself well inside the year. Do this sum with your own rate rather than a vendor's case study.
- What it does not replace. A general assistant does not read a client's books, does not produce working papers, and does not carry an audit trail. Firms that expect it to do so conclude AI "didn't work" when what failed was the fit between tool and job.
Two Things Indian Firms Should Settle With Their Own Tax View
Most global AI vendors bill from outside India, which makes the subscription an import of service. Two consequences follow, and it is worth being deliberate about both rather than discovering them at assessment:
GST. Import of services by a registered person generally attracts GST under reverse charge — the firm pays the tax itself and reports it, rather than the foreign supplier charging it. Input tax credit of that reverse-charge GST is available subject to the normal conditions, principally that the service is used in the course or furtherance of business. For a firm using the subscription in practice, that condition is ordinarily satisfied. The practical failure is not ineligibility; it is that the RCM liability is never recorded at all, because a card payment to a foreign vendor does not look like a purchase invoice.
Withholding and levies. Payments to non-resident suppliers raise Section 195 questions that depend on the nature of the payment and the treaty position. Separately, the equalisation levy that once applied to such digital transactions has been withdrawn — the 2% levy on e-commerce supply of services from 1 August 2024, and the 6% levy on online advertising from 1 April 2025 — so it no longer sits on top of these subscriptions.
Neither point is exotic. Both are routinely missed because a ₹2,000 monthly card charge does not feel like a cross-border transaction. Form your own view on the specific facts; the point here is to form one.
The subscription is, in the ordinary case, a deductible business expense.
A Decision Framework by Firm Shape
| Firm | Sensible starting position |
|---|---|
| Sole practitioner | One business-tier seat. Use it for research, drafting and structuring. Do not put client books into it. |
| 2–10 people | Business tier, a seat for everyone doing knowledge work. The admin console matters more than any feature — you need to see usage. |
| 10–50 people | Business tier at scale, plus a written internal policy on what may and may not be pasted in. At this size someone will do the wrong thing eventually; the policy is what makes that recoverable. |
| 50+ | Enterprise conversation, SSO, negotiated retention terms, and a named owner in the firm. |
| Any firm wanting AI on the client's books | A different category of product entirely — one with a contract, an audit trail, and in-country processing. A general assistant is the wrong instrument, not a cheaper one. |
The Mistake That Costs the Most
It is not overspending. Firms rarely overspend on AI subscriptions — the numbers are too small relative to a practice's cost base for that to be the real risk.
The expensive mistake is buying seats and not deciding what they are for. A seat with no defined use case gets opened twice, produces something mediocre because nobody learned how to ask, and confirms the prior that this was hype. The firms getting genuine return are not the ones that bought the best model. They are the ones that picked three tasks, got good at those, and expanded from there.
If you want a starting three: drafting observations from facts you supply, restructuring and tightening text you have already written, and understanding an unfamiliar standard or provision quickly. None of those needs client data, so none of them is blocked behind the procurement conversation.
Frequently Asked Questions
How much should a CA firm budget for AI subscriptions?
Work it per seat rather than per firm: seats × monthly price × 12, adjusted for exchange rate if billed in USD. A ten-person firm taking six to eight business-tier seats typically lands in the low lakhs per year. Test it against hours saved at your own realisation rate rather than a vendor's published case study.
Can a CA firm claim GST input credit on an AI subscription?
Where the vendor bills from outside India, the subscription is an import of service and generally attracts GST under reverse charge, with input tax credit of that tax available subject to the usual conditions — principally use in the course or furtherance of business. The common failure is not claiming credit wrongly; it is never recording the reverse-charge liability, because a card payment to a foreign vendor does not arrive as a purchase invoice.
Is a consumer subscription enough, or do we need a business tier?
For work that involves no client data, a consumer tier is often enough. The moment client data is involved you want a tier that comes with a data processing agreement and central administration — usually the business or team tier. The trigger is the contract, not the feature list.
Should each person have their own login?
Yes. Shared logins remove any record of who used what, mix conversation history across engagements, and leave you unable to answer a confidentiality question if one is ever asked. For a profession where the file is the defence, per-person seats are the minimum.
Should we buy an AI subscription or audit software?
They solve different problems. A general assistant helps a person think, write and research. Audit software works on the client's books with an audit trail behind it. Firms that expect a chat subscription to produce working papers conclude that AI does not work, when what failed was the match between the tool and the task.