Collected VAT is not operating margin
When a taxable Mexican sale includes IVA, the tax portion needs its own trail. Spending it as ordinary cash can create a funding gap when the monthly VAT return becomes due.
Mexican IVA and ISR may draw from the same invoices, but they answer different questions. IVA tracks taxable transactions and qualifying input tax. ISR follows the income-tax method assigned to the taxpayer. A single percentage swept from every bank deposit therefore gives a false sense of control.
Original Fintax post explaining the basic distinction between Mexico's IVA and ISR.
Operational comparison
| Dimension | IVA / Mexican VAT | ISR / income tax |
|---|---|---|
| Tax object | Taxable sales, services, leases, and imports | Income or taxable profit under the applicable regime |
| Typical timing | Generally cash collected and qualifying input VAT paid | Cash or accrual depending on taxpayer and regime |
| Offsets | Creditable VAT, withholdings, and eligible balances | Deductions, losses, withholdings, and provisional payments when allowed |
| Monthly character |
Article 1 of the Mexican VAT Law requires IVA to be charged expressly and separately and says it does not form part of the transaction value. Article 1-B generally ties VAT timing to consideration actually collected. The Income Tax Law then applies different accumulation and deduction methods to companies, individuals, RESICO taxpayers, lessors, and other categories.
Worked cash example
A consultant invoices MXN 116,000: MXN 100,000 for the service plus MXN 16,000 IVA. Half is collected this month. The business also pays a qualifying MXN 23,200 vendor bill: MXN 20,000 plus MXN 3,200 IVA. Ignoring withholdings, mixed activities, prior balances, and special rules, the preliminary bridge is:
| Line | Cash movement | Preliminary tax classification |
|---|---|---|
| Customer collection | +58,000 | 50,000 consideration plus 8,000 output IVA collected |
| Vendor payment | -23,200 | 20,000 expense plus 3,200 potentially creditable IVA |
| Illustrative VAT reserve |
This is not an ISR calculation
Income tax requires the taxpayer type, regime, recognition timing, deductions, withholdings, losses, and prior payments. Multiplying cash by a generic rate does not produce a defensible ISR figure.
Input IVA needs more than a CFDI
A separately stated amount is only a candidate for credit. The purchase must support taxable or zero-rated activity, meet the applicable indispensability and documentary conditions, and be effectively paid. Exempt operations, personal costs, mixed-use expenditure, missing evidence, and withheld IVA can change the month in which credit is available.
SAT's summary of the monthly IVA calculation subtracts qualifying input tax and import VAT from tax on consideration actually collected. The arithmetic is short; reconciling the evidence is where most control work sits.
Why ISR may not follow the bank statement
| Taxpayer event | Why deposits mislead |
|---|---|
| General-regime Mexican company | Income recognition can precede collection under statutory trigger rules |
| Business or professional individual | Cash receipt may matter, but deductions and payments need their own qualification |
| RESICO individual | ISR uses collected CFDI without deductions in that method; IVA remains separate |
| Customer withholding |
Five-line monthly bridge
- Revenue before IVA, classified as 16%, 0%, exempt, or outside scope.
- Output IVA invoiced, collected, pending, cancelled, refunded, or withheld.
- Purchases before IVA, separated into ISR-deductible and non-deductible items.
- Input IVA paid, creditable, restricted, withheld, or pending.
- ISR estimate under the actual regime, withholdings, provisional payments, and return variance.
Reconcile the bridge to CFDI, payment complements, banks, and the ledger. Deposits can include loans and transfers; outgoing payments can include advances, refunds, debt, and owner withdrawals. Neither total is a tax base without classification.
Liquidity errors and controls
| Error | Cash consequence | Control |
|---|---|---|
| Spending collected IVA | Monthly return is unfunded | Tax-specific reserve account |
| Crediting every vendor IVA amount | VAT liability is understated | Evidence matrix by invoice |
| Estimating ISR from net deposits |
A tax reserve without a magic percentage
- Identify output IVA actually collected rather than applying 16% to every deposit.
- Subtract only paid input IVA that currently meets credit requirements.
- Estimate ISR using the taxpayer's real statutory method.
- Track withholdings, carryforwards, and due dates on separate lines.
- Release excess reserve only after reconciling the filed return and payment.
Frequently asked questions
Is customer IVA income for Mexican ISR?
Separately stated IVA is not part of the VAT transaction value. ISR income must be determined under the applicable income-tax provisions rather than treating output tax mechanically as the taxpayer's own sale.
Does an ISR-deductible purchase always create input VAT credit?
No. The systems overlap but have distinct conditions, and exempt or mixed activities can restrict creditability.
Why can ISR rise in a low-cash month?
Possible causes include accrual recognition, a profit coefficient, limited deductions, missing withholdings, or unapplied provisional payments. The correct explanation depends on the regime.
Is monthly IVA provisional?
Under the general VAT framework, monthly IVA payments are final. Monthly ISR is commonly provisional against annual income tax, subject to regime-specific exceptions.
Official sources
Review the current VAT Law, Income Tax Law, and SAT individual filing service. Confirm the taxpayer's RFC obligations before building a cash reserve.
