A Vietnamese company files its VAT return and its personal income tax withholding return either monthly, by the 20th of the following month, or quarterly, by the last day of the first month of the following quarter (Law on Tax Administration, Law 38/2019/QH14). Which one applies is not a matter of preference. Under the rules that have applied since 2020 in Decree 126/2020/NĐ-CP, the period depends mainly on the company's revenue in the previous year, with newly started businesses treated separately; PIT withholding generally follows the VAT period. The company assesses its own period, and the tax authority checks it.
For most large foreign-invested companies the answer is simply "monthly". The question matters for new subsidiaries, small service companies, representative offices and groups with several entities of different sizes, where one entity may be monthly and another quarterly. The implementing rules were reissued in mid-2026 — Decree 252/2026/NĐ-CP guides the Law on Tax Administration from 1 July 2026 — so check the current criteria before you rely on the period you used last year.
What the filing period governs, and what it does not
| Follows the monthly or quarterly period | Does not follow it |
|---|---|
| VAT return | Corporate income tax: paid provisionally each quarter, finalised annually |
| PIT withholding return for employees and other recipients | Annual CIT and PIT finalisation: last day of the third month after year end |
| Payment of the VAT and PIT declared on those returns | Foreign contractor tax, declared per payment or monthly depending on registration |
| Event-driven filings such as registration changes |
A useful consequence: a quarterly filer still pays provisional CIT quarterly, but a monthly filer does not start filing CIT monthly. The period question is essentially a VAT and PIT question.
How the period is decided
The rules have long worked in three steps, and it is worth checking each against the current decree:
- Revenue test. A company whose revenue from sales of goods and services in the previous year is above a threshold set in the decree files monthly; below it, the company may file quarterly. The threshold and the definition of revenue are in the implementing rules; read them rather than using a number remembered from a seminar.
- New businesses. Businesses that have just started operating have been allowed to file quarterly for an initial period, before the revenue test can be applied to a full year. A new FIE should confirm how its first period is counted if it started mid-year.
- Self-assessment and notification. The company determines its period each year based on the previous year's revenue. When it changes from one period to the other, it notifies the tax authority as the rules require, and the new period applies for the whole calendar year.
Some situations are outside the revenue test, for example certain categories of taxpayer that must file monthly regardless of revenue. If your company is in a specialised sector or is part of a group that files centrally, confirm its position with your adviser.
Monthly against quarterly: what actually changes
| Monthly | Quarterly | |
|---|---|---|
| Returns per year (VAT and PIT each) | 12 | 4 |
| Deadline | 20th of the following month | Last day of the first month of the following quarter |
| Cash timing | Smaller, frequent payments | Larger payments, later on average |
| Error detection | Faster: problems surface within weeks | Slower: an error can repeat for three months |
| Workload | Steady | Peaks in January, April, July, October |
Quarterly filing looks attractive because the tax is paid later. But the reconciliation work does not shrink: e-invoices issued and received still need to be matched to the ledger every month if you want to catch problems early. Many companies that file quarterly still close VAT monthly internally, and only the submission is quarterly.
When a company switches, and how to handle the first year
The switch usually happens in one of three situations:
- A new subsidiary grows. It started quarterly, its first full year of revenue crosses the threshold, and from the following January it files monthly.
- A business shrinks or restructures. Revenue falls below the threshold, for example after a business line is moved to another group entity, and quarterly filing becomes available.
- A company corrects a wrong assumption. Someone realises that the company has been filing quarterly when the rules required monthly, or the reverse.
In the year of a switch, the practical risks are all about the first return under the new period. Put the new deadlines on the calendar before January; make sure the e-tax account shows the period you expect; tell payroll, because the PIT withholding return usually moves with the VAT return; and check the first payment falls on the right date. Where a company discovers it filed on the wrong period, it should correct under the procedure in the current rules with its adviser, and assess any late-payment interest that follows — the rate has long been 0.03% per day on tax paid late, but check the rate in force.
A hypothetical subsidiary through its first three years
Suppose a foreign group sets up a Vietnamese engineering services company that starts operating in August. The pattern below is typical; the exact treatment depends on the current rules and should be confirmed.
- Year 1 (August to December). As a newly started business, it files VAT and PIT withholding quarterly. Its first quarterly return covers the part of the quarter in which it operated. The team closes VAT monthly in the ledger anyway, so that e-invoices issued and received are matched while memories are fresh.
- Year 2. The company assesses its period again under the rules for businesses in their initial period, and continues quarterly if it still qualifies. Revenue grows quickly as the group moves regional contracts to Vietnam.
- Year 3. Year 2 revenue is above the threshold in the decree. From January the company files monthly, notifies as required, and the payroll team moves the PIT withholding return to the monthly rhythm at the same time. The first monthly VAT return, for January, is due by 20 February — in a year when Tết may fall in that window.
The mistakes in this story, when they happen, are always at the transitions: the first return after start-up, and the first month after the switch. Everything in between is routine.
What a quarterly filer should still do every month
- Download and match e-invoices issued and received against the ledger, and chase suppliers for missing or wrong invoices before the quarter ends.
- Check foreign contractor tax on every overseas payment made that month; it does not wait for the quarter.
- Review payroll withholding for new joiners, leavers and one-off payments such as bonuses, so the quarterly PIT return is a summary rather than a reconstruction.
- Update the cash forecast with the VAT and PIT that will fall due at the end of the first month of the next quarter.
Handled this way, the quarterly return is filed from numbers that have already been checked three times.
Groups with several entities
Foreign groups often have a large operating company and one or two small entities — a trading company, a service company, a holding vehicle. Each entity has its own period. A shared service team that runs one calendar for all of them will eventually file one entity on the wrong rhythm.
What helps:
- A one-line register per entity: tax code, filing period for the year, date assessed, who assessed it.
- A January check each year: previous-year revenue per entity against the current threshold, and any notification needed.
- For branches and dependent units that declare separately, the same line in the register, with a note on whether the unit declares VAT itself or through the head office.
This takes an hour a year. Correcting a year of returns filed on the wrong period takes considerably longer.
Cash flow: using the period without gaming it
A quarterly filer pays VAT on average later than a monthly filer. That is a lawful consequence of the period, not something to engineer. What is not acceptable is manipulating reported revenue — delaying invoices, splitting sales across entities without commercial reason — to stay under the threshold. E-invoice data reaches the tax authority invoice by invoice, and timing of invoices is governed by the invoice rules, not by the filing calendar.
Where cash is tight, the legitimate levers are elsewhere: forecasting VAT payable accurately, claiming input VAT on time with complete documents, and applying for refunds where the company qualifies. For a monthly filer, the 20th of each month is a fixed outflow that treasury should plan for like payroll.
Where to check your period
- Your company's e-tax account — the returns the system expects and their periods.
- Your previous year's revenue — from the audited or draft financial statements, measured as the rules define it.
- Your managing tax office — for confirmation in unusual cases. The tax administration now has three tiers: the central Tax Department, provincial and city tax offices and grassroots tax offices.
For a wider view of all recurring deadlines, see our guide to the full-year calendar in this section.
Frequently asked questions
Can we choose to file quarterly because it is easier?
No. The period is set by criteria in the rules, mainly previous-year revenue and whether the business is newly started. If the company qualifies for quarterly filing, it may use it; otherwise it files monthly.
Does our PIT withholding return follow the VAT period?
Generally yes, PIT withholding returns follow the same monthly or quarterly period as VAT. Confirm in your e-tax account and tell payroll when the period changes.
Does a monthly VAT filer also file CIT monthly?
No. CIT is paid provisionally each quarter and finalised annually regardless of the VAT filing period.
We started operating in September. Are we monthly or quarterly?
Newly started businesses have been allowed to file quarterly for an initial period. Check how the current rules count that period for a mid-year start and confirm with your managing tax office if unsure.
When does a change of period take effect?
The period is assessed for a calendar year, so a change normally applies from the first period of the new year after the company notifies as required.
We realised we should have filed monthly last year. What should we do?
Discuss with your adviser how to correct under the current procedure, and calculate any late-payment interest arising. Correcting early is cheaper than waiting for a tax audit to find it.
