Quarterly provisional CIT in 2026: the new deadline and the 80% rule

From 1 July 2026, provisional corporate income tax (CIT) for each quarter is due on the last day of the first month of the next quarter. It used to be the 30th. For 2026 that means Q2 by 31 July 2026, Q3 by Monday 2 November 2026 (31 October is a Saturday) and Q4 by Monday 1 February 2027 (31 January is a Sunday). The four quarterly payments together must reach at least 80% of the CIT you finally owe for the year. Any shortfall below that 80% line attracts late-payment interest.

“Provisional” means you pay part of the year’s tax in advance, quarter by quarter, and settle the exact figure when you file the annual finalization return. There is no quarterly CIT return to file. You just pay, against the right period, on time.

If you are used to estimated tax in another country, the logic is familiar. The difference is the 80% test, which is checked against your final number, not against last year’s.

2026 due dates

The change comes from Article 24(2) of Decree 252/2026/NĐ-CP, which implements the new Law on Tax Administration (108/2025/QH15). Q1 2026 still fell under the old “30th” rule, but April has 30 days, so nothing changed in practice.

If your company qualifies under Decree 245/2026/NĐ-CP, Q2 provisional CIT can be paid up to 3 months later (by 2 November 2026) and Q3 up to 2 months later (by 30 December 2026). You must send a request to the tax office by 2 November 2026. See our post on the 2026 tax payment extension.

Which rate, and who does not pay at all

You need your rate before you can estimate anything. The CIT Law 67/2025/QH15 sets three:

• 15% if total annual revenue is VND 3 billion or less.
• 17% if total annual revenue is over VND 3 billion and up to VND 50 billion.
• 20% otherwise.

The revenue that decides your rate is the revenue of the previous tax year, as shown in last year’s finalization return (Official Letter 820/CST-TN of 2026 confirms this). The reduced rates do not apply if your company is related to an enterprise that does not itself qualify, and they do not cover certain income such as gains on capital or real estate transfers. If your Vietnamese company is a subsidiary of a larger foreign group, check this point with us before assuming 15% or 17%.

Decree 141/2026/NĐ-CP adds an exemption for very small companies: an enterprise with total annual revenue of VND 1 billion or less is exempt from CIT, from the 2026 tax year. A new company that expects less than VND 1 billion in its first year does not make provisional payments. If revenue ends up above VND 1 billion, the tax is declared and paid at finalization without late-payment interest for the quarters not prepaid.

Worked example: a VND 6 billion company

A limited company selling office equipment in Gia Định ward (old Bình Thạnh district), nine staff. Revenue in 2025 was VND 5.4 billion, so its 2026 rate is 17%. The 2026 plan: about VND 6 billion in revenue at roughly a 9% pre-tax margin.

Our method for this client: close the books each quarter, take that quarter’s actual profit, multiply by 17%, pay a few days early. We do not split the annual estimate into four equal parts, because Q4 is usually the strongest quarter.

The 80% check before the Q4 deadline

In mid-January 2027, once December is closed, we will prepare a draft finalization and add back expenses the tax office will not accept. Suppose they are VND 25 million of 13th-month salary paid in cash to three people (each payment over VND 5 million with no bank transfer record) and VND 15 million of administrative fines (traffic fines on the delivery van). Taxable income becomes 560 + 40 = VND 600 million.

• CIT for the year: 600 million × 17% = VND 102 million.
• The 80% line: 102 × 80% = VND 81.6 million.
• Paid in Q1 to Q3: VND 61.2 million.
• Minimum Q4 payment: VND 20.4 million.

We would then suggest paying VND 40.8 million for Q4, the full VND 102 million. The last 20% carries no interest if paid by 31 March 2027, but paying it now keeps the finalization clean.

If Q4 comes up short

Say only VND 15 million is paid for Q4. Total prepaid is VND 76.2 million, VND 5.4 million below the 80% line. Interest at 0.03% per day runs on that VND 5.4 million from the day after the Q4 deadline (2 February 2027) until the day before it is paid. Paid on 31 March 2027, that is 57 days, about VND 92,000.

Small money. But it sits on the company’s tax record, and real shortfalls are often much larger than this one when nobody does a January draft.

Estimating profit when the books are not closed

Many small companies do not close their books quarterly. Two practical ways to estimate:

1. Last year’s margin. If 2025 profit was 8% of revenue, take this quarter’s revenue × 8% × your rate. Quick, good enough for Q1 to Q3.
2. Year to date. At each quarter end, add up revenue and costs since January and subtract what you have already prepaid. More accurate, but needs current books.

Either way, base Q4 on the full year, including the costs that will be disallowed. If you have losses from earlier years not yet used (they can be carried forward for up to five years), take them into account.

Where people usually slip

• Paying nothing for three quarters and everything in Q4. Legal only if Q4 brings you to 80% on time. The risk is a tight January, a partial payment, and interest on the gap.
• Using book profit and forgetting disallowed costs. Salary or supplier payments of VND 5 million or more made in cash, administrative fines. The January draft in the example above exists to catch exactly these.
• Using the wrong rate. A company with VND 2.9 billion revenue in 2025 that grows to VND 6 billion in 2026 still pays 15% for 2026, because last year decides. We have also seen companies prepay at 20% all year because nobody told them about 17%.
• Choosing the wrong period on the payment slip. The money arrives but is booked to a different quarter or tax code, and the quarter you meant still shows as owed. It can be fixed, but it takes weeks.
• Prepaying under VND 1 billion. From 2026 a new company expecting less than VND 1 billion does not prepay. Amounts already paid for Q1 2026 can be refunded or offset.

When to bring in an accountant

The 80% rule is only safe if your books are current every quarter. If the books are first opened in March of the next year, your provisional payments are guesses.

Our bookkeeping and financial statements service is VND 3 million a month before 8% VAT, for companies under 20 staff with up to 80 documents a month. It includes quarterly closes, provisional CIT calculations, a January draft finalization and the annual statements, with a short monthly summary in English. See our pricing, try the fee calculator, or book a 30-minute call with Tài to check whether your prepayments reach 80%. All quarterly dates are on the 2026 tax calendar; VAT periods are covered in monthly or quarterly VAT filing, and the year-end in CIT finalization and financial statements for 2026.

Sources and update

Based on the Law on Tax Administration 108/2025/QH15, Decree 252/2026/NĐ-CP of 30 June 2026 (Article 24(2) on provisional payment dates, effective 1 July 2026), the rule that four quarterly prepayments may not fall below 80% of the finalized CIT, the CIT Law 67/2025/QH15, Decree 320/2025/NĐ-CP (15% and 17% rates; payments of VND 5 million or more must be non-cash to be deductible), Official Letter 820/CST-TN of 2026, Decree 141/2026/NĐ-CP (CIT exemption at VND 1 billion revenue or less) and Decree 245/2026/NĐ-CP on extensions. Last checked 4 October 2026. The figures in the example belong to a hypothetical company.