A practical, everything-you-need-to-know guide. General information only, not legal advice.

1) The 30-day rule—what it actually covers

Capital Gains Tax (CGT) in the Philippines is a final tax due on certain sales or dispositions:

Sale/exchange of real property classified as capital asset (i.e., not used in trade or business): 6% of the higher of the gross selling price or the fair market value (FMV) on the date of sale.
Sale/exchange of shares of stock in a domestic corporation not traded through the local stock exchange: 15% of net capital gain.

For both categories, the law imposes an early filing/payment window:

Real property (capital asset) — File and pay within 30 days from the date of the sale or disposition (practically, the date of notarization of the deed of sale, deed of exchange, or dation in payment).
Unlisted domestic shares — File and pay within 30 days from the date of each transaction. (There is also an annual information return to consolidate the year’s transactions.)

This 30-day deadline is independent of title transfer. Missing it triggers surcharge, interest, and compromise penalties.

2) Who is taxed and who files?

Seller/transferor is liable for CGT.
Individuals and corporations alike pay 6% on the sale of real property classified as capital asset.
Ordinary assets (property used in business, inventory, or real property held for sale/lease by real estate dealers) are not subject to 6% CGT; they’re taxed as ordinary income and typically subject to creditable withholding tax (CWT) instead.
For unlisted shares, the seller pays the 15% CGT.

A buyer often cannot register the transfer (land title, vehicle CR/OR, stock certificates) without the BIR’s eCAR (Electronic Certificate Authorizing Registration), which is issued after CGT (and other applicable taxes) are settled.

3) Which forms, where to file, and what to bring

Real property (capital asset): BIR Form 1706 (Capital Gains Tax Return – Real Property).
Unlisted domestic shares: BIR Form 1707 (Capital Gains Tax Return – Shares of Stock Not Traded).
Documentary Stamp Tax (DST): generally BIR Form 2000-OT for the conveyance; required for eCAR and registration.

Core attachments (real property):

Notarized deed of sale/transfer (or dation, exchange).
Tax Declaration and zonal value/FMV references as of date of sale.
TINs of seller and buyer; valid IDs.
Proof of payment of CGT and DST, and local transfer tax later for registration.
Any authority to sell, if signing as representative.

Core attachments (unlisted shares):

Stock certificates (or certification from transfer agent/corporate secretary).
Computation of net capital gain (selling price minus adjusted cost and selling expenses).
Corporate documents establishing ownership and basis.

4) The valuation rules that drive the tax base

A) Real property (6% final tax)

Compute on the greater of:

Gross selling price stated in the deed; or
Fair market value (FMV) as of the date of sale:
- Zonal value set by the BIR, if any; or
- FMV per the latest Tax Declaration from the assessor.

The BIR will pick the highest of those numbers. You cannot use a lower declared price to reduce the 6%.

B) Unlisted domestic shares (15% final tax)

Net capital gain = selling price – cost basis (plus/minus allowable adjustments and selling expenses).
If multiple transactions in a month, file per transaction within 30 days, then include in your annual final consolidated return.

5) Installment sales, contracts to sell, and timing traps

Key distinction:

A Deed of Absolute Sale (DOAS) that transfers ownership now generally starts the 30-day clock on the date of notarization, even if the price is payable in installments. In practice, to secure the eCAR and transfer, the BIR typically requires payment of the entire 6% (based on the higher of price or FMV), irrespective of installment timing.
If parties use a Contract to Sell (title passes only upon full payment and a later deed is executed), the 30-day clock usually starts when the final deed of sale is notarized, i.e., when the actual sale is perfected and ownership is conveyed. This structure is often used so the tax becomes due only when the final conveyance occurs.

Practical takeaway: If you sign/notarize a transfer instrument that already conveys ownership, expect the 30-day CGT deadline to run from that date, even if the buyer pays over time.

6) The principal residence exemption (natural persons)

A natural person who sells their principal residence may apply for CGT exemption if all legal requirements are met, including:

Filing a sworn declaration of intent to avail (typically within 30 days from sale).
Using the proceeds to acquire or construct a new principal residence within the prescribed period (commonly 18 months from sale).
Once every 10 years limit.
Escrow or tracking of unutilized proceeds (as required) and submission of supporting proofs.

Failure to meet the conditions results in assessment of the 6% CGT plus penalties from the original 30-day due date.

7) Penalties for late filing and payment

If you miss the 30-day CGT deadline:

Surcharge: generally 25% of the basic tax (or 50% in cases of willful neglect/false return).
Interest: per annum interest computed from the original due date until fully paid (applied to the basic tax).
Compromise penalties: per BIR schedules.
Practical consequence: You cannot obtain the eCAR—so no title transfer, bank withdrawals (if asset is a time deposit or similar requiring eCAR), or stock reissuance—until taxes and penalties are cleared.

8) eCAR, ONETT processing, and title transfer sequence (real property)

Compute CGT on the higher of price or FMV, file Form 1706, and pay within 30 days.
Pay DST (Form 2000-OT) and other documentary requirements.
Submit the complete ONETT (One-Time Transaction) dossier to the BIR for eCAR evaluation.
Receive eCAR(s) (one per property/asset as applicable).
Proceed to Register of Deeds (title transfer), then LGU for transfer tax, and settle registration fees.

Note: For unlisted shares, the stock transfer agent/corporate secretary will require proof of CGT and DST before canceling and reissuing stock certificates.

9) Special situations

Dacion en pago / exchange (e.g., property for shares or settling a debt): still a taxable disposition; the 30-day rule applies from date of deed.
Judicial sales/foreclosures: taxability and timing depend on the nature of disposition (confirmation/transfer stages); plan filings conservatively around the document that effects transfer.
Co-owned property: Each co-owner reports their share of proceeds; the 6% still uses the higher of total selling price or FMV for the property, allocated to the sellers’ shares.
Overseas sellers: May authorize a local representative via SPA. Keep TIN and identity documentation aligned.

10) Checklist: paying CGT on real property within 30 days

Identify asset classification (capital vs ordinary asset).
Fix the date of sale (usually notarization date). Calendar +30 days.
Obtain zonal value/Tax Declaration FMV as of sale date; pick the highest vs selling price.
Prepare Form 1706; compute 6% of the chosen tax base.
Prepare Form 2000-OT for DST.
Gather deed, IDs, TINs, proofs (valuation, ownership).
File & pay at the RDO/authorized bank/e-channels within 30 days.
Lodge the ONETT packet for eCAR.
After eCAR: Register of Deeds → LGU transfer tax → title issuance.

11) Checklist: paying CGT on unlisted shares within 30 days

Fix transaction date; calendar +30 days.
Determine cost basis (subscription price/purchase price + allowable adjustments).
Compute net capital gain → 15% tax.
Prepare Form 1707; attach corporate/transfer papers.
Pay DST on the share transfer.
File and pay within 30 days; include transaction in the annual consolidated return.
Submit proofs to the corporate secretary/transfer agent for certificate cancellation/reissuance.

12) Planning pointers to avoid deadline pain

Structure the deal properly: If truly installment-based and you can’t fund full CGT at once, consider a Contract to Sell and issue the Deed of Absolute Sale only upon full payment, aligning the 30-day clock with actual conveyance.
Don’t under-declare the price: The BIR will use the highest of price or FMV, so under-declaration only creates penalty risk.
Paper early: If availing the principal residence exemption, file the sworn declaration within 30 days and track utilization of proceeds meticulously.
Amend if needed: You can amend a previously filed return within the prescriptive period if valuation documents change, but penalties may apply if the amendment increases the tax due.
Keep a funding buffer: Banks often require eCAR for loan take-out on the buyer side; late CGT payment can delay financing and closing.

13) Frequently asked questions

Q: Our deed was notarized last month but the LGU hasn’t released a new tax declaration. Is the 30-day deadline extended? A: No. The 30-day period runs from the date of sale/notarization. Use the available FMV (zonal/tax dec) as of that date to file and pay on time.

Q: We agreed on installments. Can we pay CGT per installment? A: If a deed already conveys the property, the BIR typically expects full CGT within 30 days based on the full tax base (higher of price or FMV). Structuring as Contract to Sell with transfer later is the usual way to align taxes with cash flow.

Q: I’m selling my principal residence. When do I file the exemption paperwork? A: File the sworn declaration within 30 days from sale, then fully utilize the proceeds within the allowable period. Failure to comply leads to assessment of 6% CGT plus penalties.

Q: What if we pay on day 45? A: Expect surcharge, interest, and compromise. You’ll still need to settle these before the BIR issues an eCAR.

Q: Is CGT always 6% for property? A: Only when the asset is a capital asset. If it’s an ordinary asset (e.g., used in business, inventory of a developer/lessor), the sale is not subject to 6% CGT; it’s ordinary income subject to CWT/VAT as applicable.

14) One-page action plan

Fix the date of sale and calendar +30 days.
Classify the asset (capital vs ordinary).
Establish the tax base (higher of selling price or FMV for property; net gain for shares).
Prepare and file the correct form (1706 for property; 1707 for unlisted shares) and pay within the 30-day window.
Settle DST and compile the ONETT dossier for eCAR.
Register the transfer (RD/transfer agent/LTO as relevant).
If claiming principal residence exemption, file sworn declaration within 30 days and track utilization.

If you share the type of asset, date of sale/notarization, selling price, and the FMV/zonal value, I can draft a deadline-proof filing checklist, compute the CGT (and DST), and outline the exact attachments your RDO will look for.