Quick Answer
To budget 2027 taxes, separate ISR, VAT, withholdings, payroll, IMSS, and annual taxes by trigger and date. Project scenarios with collections and margin, create an independent reserve, and update assumptions when approved rules exist; do not use an arbitrary percentage of sales.
Model ISR, VAT, payroll, and annual taxes by trigger, date, and scenario to build a 2027 tax reserve that truly follows your operations.
Distinguish Assumption from Rule
Label which figures are projections and update the model only with approved and published provisions.
Reserve by Trigger
| Tax | Trigger | Frequency | Source |
|---|---|---|---|
| Provisional ISR | Income and coefficient | Monthly | Schedule |
| VAT | Collections, payments, and transactions | Monthly | CFDI and bank |
| Withholdings | Payments subject to withholding | Monthly | Payroll and suppliers |
| Social Security | Staff and salary | Monthly/Bimonthly | Payroll and SUA |
| Annual | Fiscal result | Annual | Pre-closing |
Case: Reserving a fixed percentage of sales
A company sets aside 10% of each sale but has collected VAT, biweekly payroll, provisional payments, and annual taxes with seasonality. Build a model by tax and scenario, and update monthly with actual data.
The tax reserve must model triggers and dates; a single percentage can leave excess cash or a serious shortfall.
— Fintax
Fiscal Budget Inputs
- Sales, collections, and margin by month.
- Projected provisional and annual ISR.
- Collected VAT, creditable VAT, and dates.
- Payroll, IMSS, and Infonavit.
- Scenarios, responsible parties, and reserve account.
Budgeting is not guessing the rate
A fiscal budget translates operations into cash outflow dates. Separate own taxes, withheld taxes, payroll, social security, and annual events.
For 2027, use current rules as a base and mark assumptions to update when legislation is approved. The model must be changeable without rebuilding.
Five-layer Model
- Build a monthly base.
- Model each tax.
- Assign date and responsible party.
- Create scenarios and reserve.
- Update with actuals and approved rules.
Why the reserve fails
- Using an arbitrary percentage.
- Budgeting sales but forgetting collections.
- Mixing withheld taxes with free cash.
- Not updating the model with actual closings.
Sources and further reading
Consult official sources: ISR provisional payments, SAT calendar, IMSS SUA.
To complete the process within Fintax, review: cash flow and taxes, fiscal closing, annual corporate tax return.
Frequently Asked Questions
What percentage of sales should I set aside?
There is no universal percentage. Model taxes, margin, collections, and dates specific to your business.
Should I use 2026 laws for 2027?
Use them explicitly as a base and update only when changes are approved and published.
Where should I keep the reserve?
Define a separate account or control and authorized disposition rules.
What to do now
Turn this review into a file with responsible party, date, source, and evidence. If there is a material difference, an overdue obligation, or a decision that changes the calculation, validate the case with your accounting responsible before filing, canceling, or paying.
