Every new tax season starts with the same paperwork per client: an engagement letter, a tax organizer collecting the same personal and financial details as last year, and often an IRS authorization form. For a firm with more than a handful of clients, that's the same names, addresses, and filing details retyped across dozens of near-identical documents before any actual tax work begins.
Accountants and tax preparers auto-fill engagement letters and tax organizers by saving each client's personal, business, and filing details as a reusable profile once, then letting an AI form-filler map those values onto every engagement letter, organizer, or authorization form for that client. Returning clients' prior-year details carry forward, so only what changed needs review.
Why does tax season paperwork take so long before the actual work starts?
Because the engagement letter, the organizer, and any authorization forms each ask for overlapping information — client name, entity type, EIN or SSN, address, filing history — typed independently into each document. Across a full client list, that repetition is hours of transcription before a single return is prepared.
Can a returning client's details carry over from last year?
Yes. Once a client's profile exists, it persists year to year. Updating an address or adding a dependent takes seconds; everything unchanged — entity details, EIN, prior elections — carries forward automatically instead of being re-collected from scratch each engagement.
How do engagement letters fit this workflow?
An engagement letter needs the client's legal name, entity type, and the scope of services — details that repeat on the organizer and any related forms. Filling it from the same client profile keeps the entity name and details identical across every document in the file. The service agreement template is a reasonable starting structure for a services-scope letter, or upload your firm's own engagement letter and fill it the same way.
What about IRS authorization forms like Form 8821?
Authorization forms follow the same client and preparer details as the rest of the engagement. If your firm regularly files Form 8821 to access client tax information, see the Form 8821 guide for that form specifically — it fills from the same client profile as the engagement letter and organizer. Power-of-attorney authorizations follow a similar pattern; the power of attorney template is a related starting point.
Can a firm fill the same organizer for its entire client list at once?
Batch fill applies one organizer or engagement letter template across every client profile in a single run — useful at the start of tax season when the same documents need to go out to a full client list at once, rather than one at a time.
Frequently asked questions
Is this a substitute for tax preparation software?
No. It fills the administrative documents — engagement letters, organizers, authorization forms — from saved client data; it doesn't prepare or file returns. Use it alongside your existing tax prep software, not instead of it.
Can each staff member access the same client profiles?
Yes. Profiles are reusable across a team, so any preparer working a client's file can generate documents from the same saved data without re-entering it.
Is there a free option to try before tax season?
Yes. The free plan covers up to 10 filled documents a month with no credit card — enough to test the workflow on a handful of returning clients before the busy season starts.
How is client financial data protected?
Filly encrypts stored data, publishes its sub-processors, doesn't use documents to train AI, and supports deletion on request — see the security page. This is a form-filling tool, not tax or legal advice.