Engagement letters when specialty tax work is in the return

When a boutique's study rides into a return the firm signs, the engagement letter is where the firm decides — in advance and in writing — which risks it is accepting and which it is not. A letter drafted for ordinary compliance work does neither. Four clauses do most of the work: a scope limit, a reliance-on-specialist provision, an exam-support carve-out, and honestly drafted indemnity language.

Scope: say what the firm is not doing

The letter should identify the specialty deliverable by provider and type — "the research credit study prepared by [Provider] for tax year 2025" — and state that the firm's services are limited to preparing the return incorporating it. Three sentences earn their keep:

• The firm has not performed, audited, or verified the study, and expresses no opinion on its methodology or conclusions.
• The firm will review the deliverable to the extent necessary for return preparation, including reconciling its totals to the return and the client's records.
• The firm may decline to reflect any position it reasonably believes lacks the support required for a signing preparer, or may condition signature on disclosure (Form 8275).

That last reservation matters most. Under Circular 230 §10.34 a practitioner may not sign a return containing a position without a reasonable-basis floor, and under Section 6694 undisclosed positions need substantial authority — the letter should preserve the firm's exit before the deadline pressure arrives. The mechanics of that exposure are covered in preparer penalties under Section 6694.

Reliance on specialists: make the allocation explicit

A reliance clause states that in preparing the return the firm will rely on information, analyses, and conclusions furnished by the client and its specialists; that the client is responsible for the completeness and accuracy of information given to both firms; and that responsibility for the study's technical content rests with the provider under the client's separate agreement with it. This tracks the regulatory reliance framework — Treas. Reg. §1.6694-1(e) permits good-faith reliance on another advisor's work, with the full text in Title 26 of the eCFR — and, in a later dispute, points the client's memory at the correct defendant. The clause is only as strong as the diligence behind it: reliance on a provider the firm never vetted is hard to call reasonable, which is why the letter should sit on top of a standing vetting process like the one in our provider-vetting playbook.

Exam support: carve it out, price it later

If the credit or the depreciation is examined, three distinct jobs appear: representing the taxpayer, defending the study, and explaining the return. The letter should carve examination and controversy work out of the preparation engagement entirely — separately engaged, separately billed — and note that defense of the study's methodology is the specialist's obligation under whatever exam-support terms the client obtained from it. This does two things: it keeps the firm from having silently promised free audit defense of work it did not perform, and it forces the client to look at the boutique's support terms now, while choosing providers, rather than during an exam. If those terms turn out to be vague, that is information the client needs before filing, not after.

Indemnity realism

Firms sometimes ask clients to indemnify them for penalties arising from specialist-provided information; clients sometimes ask the reverse. Both deserve modest expectations. An indemnity cannot shift Section 6694 or Circular 230 exposure — those run to the preparer personally, and public policy plus many state accountancy rules limit exculpation for a professional's own negligence. Some E&O carriers also treat broad indemnities given by the firm as excluded contractual liability; check the policy before promising anything (see professional liability in tax claims). What indemnity language usefully does is narrower: it documents that the client — not the firm — chose the specialist, and it sets the expectation that costs flowing from the study's failures belong upstream. Draft it as allocation of responsibility between client and firm for third-party work product, not as armor.

Two final habits. Refresh the letter annually — a 2024 letter does not cover the 2025 study — and attach or reference the specific deliverables each year, because the firm that documents the boundary before signing rarely has to litigate it after.