A quote of MXN 2,500 per month and a quote of MXN 4,000 do not yet tell you which service costs less. The first may charge separately for the annual return, payroll, amended filings, SAT notices, and prior-period cleanup. The second may include work you do not need.
Compare the cost of unresolved work
When two proposals look similar, compare what happens when information arrives late, a CFDI must be corrected or the authority sends a notice. Confirm whether those cases are included, how they are approved and what evidence is delivered. The cheapest monthly fee can become expensive if every exception is undefined.
Compare what each quote would cost over twelve months using the same workload. Ask which returns, reports and follow-up work are included, then add the fees for anything your business needs that falls outside the monthly price.
Give every provider the same fact sheet
A firm cannot price the work responsibly from the words "small business." Send a one-page operating profile:
| Input | What to disclose |
|---|---|
| Taxpayer | Individual or legal entity, tax regimes, activities, and registered obligations |
| Volume | Average monthly issued and received CFDI, bank transactions, and cash sales |
| Accounts | Banks, payment processors, credit cards, loans, and foreign-currency accounts |
| Payroll | Employees, payroll frequency, variable pay, and terminations |
| Operations | Inventory, imports, exports, fixed assets, related parties, and branches |
| Current status | Last return filed, outstanding notices, unreconciled months, and tax debts |
| Reporting | Required close date, cash-flow report, financial statements, and management detail |
If one provider prices 50 monthly transactions and another assumes 500, their fees are answering different questions. Ask each provider to write the volume assumptions into the proposal and state what happens when the business exceeds them.
Check how much of the work is included
Two taxpayers in the same regime may need very different work. One sends five invoices and receives payment immediately. The other has partial collections, payroll, several bank accounts, inventory, and cancellations every week.
The following examples show how the amount of work included can differ:
| Service | Work normally expected | What may remain with the client |
|---|---|---|
| Filing only | Prepare and submit listed returns from client-provided figures | Reconciliations, bookkeeping, CFDI review, and source-data quality |
| Monthly close and compliance | Book transactions, reconcile accounts, prepare workpapers, file returns, and report exceptions | Internal approvals, missing documents, and operating decisions |
| Close, compliance, and advisory | Monthly close plus forecasts, decision support, and scheduled advice | Execution of business decisions and specialized legal work |
These are descriptions, not official categories. A provider can use different names. Read the deliverables.
Calculate the twelve-month cost
Use the same formula for every proposal:
Annual cash outlay = monthly fee × 12 + onboarding + separately billed annual work and payroll + expected extras + taxes on the fee.
Include each charge once. If payroll or the annual return is already covered by the monthly fee, do not add it again.
Build a sheet with actual quantities:
| Cost line | Proposal A | Proposal B | Proposal C |
|---|---|---|---|
| Monthly fee multiplied by 12 | Enter quoted amount | Enter quoted amount | Enter quoted amount |
| Onboarding and opening balances | Enter quoted amount | Enter quoted amount | Enter quoted amount |
| Cleanup of prior months | Enter quoted amount | Enter quoted amount | Enter quoted amount |
| Annual return and year-end close | Enter quoted amount | Enter quoted amount | Enter quoted amount |
| Payroll processing | Enter quoted amount | Enter quoted amount | Enter quoted amount |
| Informative returns | Enter quoted amount | Enter quoted amount | Enter quoted amount |
| Amended returns allowance | Enter quoted amount | Enter quoted amount | Enter quoted amount |
| SAT notice or clarification allowance | Enter quoted amount | Enter quoted amount | Enter quoted amount |
| Refund or balance-in-favor work | Enter quoted amount | Enter quoted amount | Enter quoted amount |
| Software and storage | Enter quoted amount | Enter quoted amount | Enter quoted amount |
| Cancellation or handoff fee | Enter quoted amount | Enter quoted amount | Enter quoted amount |
| VAT on professional fees | Enter quoted amount | Enter quoted amount | Enter quoted amount |
| Total expected annual cash outlay | Calculate total | Calculate total | Calculate total |
Do not set every uncertain item to zero. Use a realistic quantity based on the last year. If the business filed three amended returns and received one SAT notice, price that history under each proposal.
Show two totals: professional fees before VAT and cash paid including VAT. Input VAT may be creditable when the taxpayer and transaction meet the legal requirements, so it should not automatically be treated as a permanent expense. It still affects the payment leaving the bank.
Define what the monthly fee buys
"Monthly accounting" is too vague for a contract. The scope should name the work and the output.
| Area | Work to name | Evidence the client receives |
|---|---|---|
| Bookkeeping | Record bank, sales, expenses, payroll, loans, and owner transactions | Ledger or transaction detail |
| Reconciliation | Reconcile banks, receivables, payables, taxes, and key balance-sheet accounts | Reconciliation file and exception list |
| CFDI | Review issued, received, cancelled, replacement, payment, and payroll CFDI | Difference report and correction requests |
| Tax | Prepare each listed provisional, definitive, informative, and annual return | Workpaper, filed return, receipt, and payment reference |
| Payroll | Calculate payroll and statutory deductions for the agreed population | Payroll summary, CFDI status, and payment files |
| Reporting | Produce the agreed financial or cash report by a set date | Named report with delivery deadline |
| Advice | Answer questions within defined subjects, hours, and channels | Written response or scheduled meeting |
A filed-return receipt proves that a return was submitted. It does not show how the provider reached the figures. Ask for the workpaper and the list of unresolved differences.
Price the exceptions before signing
Ask for prices or billing rules for work outside the monthly service, including:
- amended return caused by late client information;
- amended return caused by provider error;
- response to a SAT invitation, notice, or formal requirement;
- refund or offset request;
- payroll termination or retroactive correction;
- new bank account, branch, employee, or tax obligation;
- prior-period reconstruction;
- shareholder meeting, loan agreement, or corporate record;
- urgent work requested outside the close calendar.
Provider errors and client changes should not use the same billing rule. The contract should say who pays when a return must be corrected because the accountant used the wrong rate, missed an on-time document, or filed after the agreed deadline.
Compare deadlines and responsibilities
Ask for a close calendar rather than a promise to "file on time."
| Step | Client responsibility | Provider responsibility |
|---|---|---|
| Source data | Deliver bank records, sales, payroll changes, and missing documents by the cutoff | Confirm receipt and identify unreadable or missing items |
| Reconciliation | Answer transaction questions and approve classifications | Match records, quantify differences, and maintain the exception list |
| Tax review | Approve the payment and disclose late changes | Deliver calculation and workpaper with review time |
| Filing | Provide authorization or signature when required | File the approved return and send the receipt |
| Archive | Retain business source records | Return agreed ledgers, workpapers, and filing evidence |
Agree on what happens when either side misses a date, including how the delay will be reported and whether it changes the fee.
Check who will prepare and review your work
Verify the responsible accountant's professional license in Mexico's National Registry of Professionals. Ask who reviews the work and who signs or submits each return.
A regular monthly accountant does not need to appear in the SAT registered-accountant list merely to keep books or file ordinary returns. That registration matters for specific work such as tax audit reports. Our guide to the SAT public accountant registry explains the difference.
After checking the license, ask who reviews the monthly calculations and how that review is recorded. A sample reconciliation or monthly report will help you understand the work you can expect.
Protect tax credentials and business data
Mexico's SAT describes the e.firma as unique, created under the signer's exclusive control, and legally equivalent to a handwritten signature. Treat its private key and password accordingly.
Before giving access, ask:
- Which SAT tasks require the taxpayer's e.firma, CSD, or password?
- Can the provider prepare the filing while the taxpayer or legal representative signs it?
- Where will credentials and XML files be stored?
- Which staff members can access them?
- Is access logged and protected with multifactor authentication where available?
- What is revoked or returned when the contract ends?
- How will a data incident be reported?
Do not email the e.firma private key and password in the same message. A low monthly fee is irrelevant if the access model lets former staff or subcontractors keep signing credentials.
Compare the services you need alongside the annual price
Review each proposal in two stages. First score the service:
| Criterion | Suggested weight |
|---|---|
| Scope matches the operating profile | 25 |
| Monthly reconciliation and evidence | 20 |
| Tax returns and annual work are explicit | 15 |
| Deadlines, communication, and escalation | 15 |
| Credentials, security, and access control | 10 |
| Extra-fee schedule | 10 |
| Exit and data handoff | 5 |
Choose the criteria that matter to your business, then compare annual costs for firms that meet them. If one quote covers filing only and another includes bookkeeping and reconciliation, account for who will do the remaining work and what that will cost.
Weights can change. A company with payroll may assign more points to payroll controls. A taxpayer facing a notice may care more about representation and document reconstruction.
Watch for answers that hide the scope
Warning signs include:
- a fixed fee quoted before anyone asks about regime, volume, or backlog;
- "all returns included" with no list;
- no workpapers, reconciliations, or filing receipts;
- unlimited advice with no definition of topic or response time;
- no distinction between ordinary questions and a formal SAT response;
- pressure to hand over the e.firma without an access policy;
- extra work billed at an unspecified rate;
- no clause requiring delivery of XML, ledgers, workpapers, and receipts at exit.
The opposite problem exists too. A long proposal can bury weak service under pages of exclusions. Ask the provider to walk through one normal month, one late document, and one SAT notice.
Make the exit part of the purchase
The client should own or receive an export of:
- chart of accounts and opening balances;
- transaction-level ledger;
- bank reconciliations;
- tax workpapers and loss schedules;
- issued and received XML archive;
- filed returns, receipts, and payment records;
- payroll records;
- list of open items and deadlines.
Set the delivery format, timing, and fee in the contract. Without a handoff clause, changing accountants can turn into a second onboarding project.
Questions to ask before accepting a proposal
- Which returns and periods are included?
- Is the annual close included in the monthly fee?
- Which accounts do you reconcile and how often?
- What do I receive each month besides filing receipts?
- Who prepares, reviews, and files the work?
- What information must I send, in what format, and by what date?
- Which events change the fee?
- How do you price corrections caused by your error?
- How do you handle a SAT notice?
- How do you store credentials and client data?
- What will you deliver when the engagement ends?
- Can you show a redacted example of the monthly package?
Ask the firm to add any agreed changes to the proposal before you sign. Keep that version with the contract so you can refer to the same terms later.
How Fintax presents the comparison
You can review Fintax's current accounting plans and request a consultation for operations that do not fit a standard plan. Compare the proposal with the same annual-cost sheet and technical score used for any other provider.
Frequently asked questions
What determines accounting service costs in Mexico?
Taxpayer type, regimes, transaction and CFDI volume, bank accounts, payroll, inventory, foreign operations, reporting needs, backlog, and response work all affect the fee.
Is the annual return normally included in a monthly fee?
There is no universal convention. The proposal should say whether preparation, year-end adjustments, filing, workpapers, and post-filing corrections are included.
Should I choose a fixed fee or an hourly fee?
A fixed fee works when the recurring scope and volume limits are clear. Hourly or event-based pricing can fit cleanup, SAT responses, and projects with uncertain effort. Many engagements use both.
What should I receive every month?
Receive the reports and records listed in your agreement. For a service that includes the monthly close, these would normally cover reconciliations, tax calculations, filed returns, receipts, payment references and unresolved items. A filing-only service may leave the preparation of those records to you.
Official links to complete the task
Open official services from a new browser tab, confirm the taxpayer and period, and save the resulting acknowledgment or evidence with the case.
