Quotations with payment instalments: how to set them, bill each one and collect in full

A quotation with payment instalments states from the start how the total will be billed: how many instalments, what percentage each, when, and on what condition. For example 30% on signing, 40% on the first delivery and 30% on completion. Once the instalments sit on the quotation, the people selling and the people chasing the money work from the same numbers, and each instalment can be billed without recalculating anything.

Why project work should carry instalments on the quotation

• The client sees before signing what they pay, when, and for which deliverable.
• Money arrives with the work instead of all at the final handover.
• Billing does not mean digging through chats and emails to find what was agreed.
• The owner knows which months have instalments falling due and can plan cash flow.

Setting instalments without mistakes

1. All instalments must add up to 100% of the quotation value. Change the price without changing the instalments and every figure is off.
2. Each instalment needs a condition you can check, such as “prototype delivered”, not “half the work done”.
3. Each instalment needs a payment term, such as 30 days from the billing date.
4. Work out VAT and withholding tax per instalment. When the client withholds tax, the cash received is less than the invoice.
5. Never overwrite a quotation that has been sent. Issue a revision so you can always see which figures the client saw.

Example: a 200,000 baht job in three instalments

Take a 200,000 baht job before VAT, split 30% / 40% / 30%. The provider is VAT-registered and the client is a company that withholds 3% service tax on the pre-VAT amount. (The rate is only an example: the real rate depends on the type of income and the payer, so check it with your accountant.)

• Instalment 1 (30% on signing): 60,000 + VAT 4,200 = 64,200 baht, 1,800 withheld, 62,400 baht received.
• Instalment 2 (40% on first delivery): 80,000 + VAT 5,600 = 85,600 baht, 2,400 withheld, 83,200 baht received.
• Instalment 3 (30% on completion): 60,000 + VAT 4,200 = 64,200 baht, 1,800 withheld, 62,400 baht received.

The invoices add up to 214,000 baht, but 208,000 baht reaches the bank. The 6,000 baht difference is tax withheld, which you can claim as a tax credit when filing, with the withholding tax certificates as evidence. That is why certificates should be tracked per instalment, not chased at year end.

Billing one instalment at a time and chasing receivables

• Instalments that are due for billing but not billed yet.
• Overdue bills, sorted by age.
• Quotations sent more than 7 days ago with no answer.
• Withholding tax certificates not yet received.

Where QuoteDesk helps

QuoteDesk is quotation, billing and deal tracking software. Quotations are built from the deal and a service catalogue, with discount, VAT and withholding tax worked out for you, the amount in Thai words, and each document issued in Thai or English. Instalments are set by percent, each with its condition and payment term, checked against the quotation value and printed on the document. A sent quotation is locked and changes go out as a revision (-R1, -R2). You bill the whole quotation or one instalment at a time, record payments with withholding tax, see receivables by age, track certificates and export a monthly CSV for the accountant.

The same instalments feed the owner’s cash runway: how many months the cash will last counting signed work only, adding work waiting for signature, or the whole pipeline.

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Quotation, Billing & Deal Tracking

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