Choose the categories together
Separate accommodation, ordinary household costs, shared meals and optional personal spending. Discuss whether groceries are pooled and whether particular items belong to the person who wants them. A clear category is more useful than deciding every small purchase individually at the checkout.
Use the real dates each person is present. If someone joins for a few days, decide which costs change and which were already committed. This is an agreement between your group, not a universal formula. Write down the decision so it does not depend on who remembers the conversation most confidently.
Record the total that was actually paid
For each shared purchase, keep the date, purpose, amount and payer. A photograph of the receipt may be enough, provided it is stored privately and everyone knows where to find it. Avoid sharing payment-card details or personal information unnecessarily.
Use the final amount, including the charges that belong to the order. Grab's food-service information distinguishes menu prices and delivery fees, while its help page explains that substitutions can change the final amount or promotion eligibility. A screenshot of the original basket may therefore differ from the amount that should enter your record.
Keep deposits separate from spending
A refundable deposit ties up money but is not automatically a final shared expense. Record who paid it, the agreement for its return and how any actual deductions will be discussed. Do not count both the deposit and a later bill as spending if one is used to settle the other.
For accommodation and utilities, retain the provider's calculation and the agreed charging method. Your household record should follow those documents rather than inserting an assumed nightly or utility rate. If something is unclear, resolve it with the provider before dividing the amount between travellers.
Make optional plans genuinely optional
Agree that a person can decline an activity or a more expensive meal without making the rest of the group uncomfortable. Decide in advance whether a shared vehicle or reservation still costs the same when fewer people join. That information lets everyone choose with a realistic understanding of the effect.
Avoid treating the least expensive preference as a problem that someone must justify. Equally, do not expect the group to fund a personal upgrade without discussion. The useful question is what arrangement everyone knowingly accepted, not whose idea sounded more exciting at the time.
Check the record regularly, briefly
Choose a short interval that suits the group, such as after several days or at the end of a week. Look for missing receipts, duplicate entries and purchases placed in the wrong category. Small corrections are easier while people still remember what happened.
Keep the conversation factual. If an item was misunderstood, clarify how similar purchases will be handled next time. A long stay will produce imperfect records occasionally; the purpose of the system is to reduce tension, not create a detailed case against a travel companion.
Use a small fictional example to test the method. If two people agree to share 2,000 equally and one has paid 1,300 while the other has paid 700, each person’s share is 1,000; a payment of 300 from the second person to the first balances that set of expenses. This is an arithmetic illustration, not a Phuket cost estimate. Keep an individual purchase or a refundable deposit outside that calculation unless you have explicitly agreed to include it, and avoid rounding away an unexplained difference.
Finish while everyone is still available
A few days before departure, list the remaining shared payments and any amount that cannot yet be finalised. Agree how the last utility calculation or deposit return will be communicated. Do not declare the account finished while a known payment is still outstanding.
Keep the final summary short: shared total, what each person paid and the agreed balance. The method has succeeded when the numbers can be understood without a long argument. It should leave you remembering the stay, rather than wishing you had started a spreadsheet before ordering the first dinner.