How can I track costs paid personally before a shared investment budget exists?

Record each payment promptly

Create a ledger with date, supplier, description, currency, amount as shown on the receipt, payer, payment method and supporting document reference. Note the property or project purpose and whether the item was a deposit, survey, travel, furnishing or other expense. Keep original invoices and proof of payment, and record refunds or credits against the related entry.

Do not assume a personally paid amount automatically creates a share of ownership, a reimbursable loan or an agreed household contribution. Record what the parties understood at the time and identify any disagreement. Avoid changing invoice details or combining unrelated costs to make the ledger appear balanced. If a payment was made in another currency, retain the transaction evidence and note any conversion separately rather than inventing a rate.

Agree a process for reviewing expenses before the shared budget is established, including who can approve further spending and how records will be stored. A qualified accountant can advise on bookkeeping and tax documentation; a Greek lawyer can advise on ownership, contracts and any repayment agreement. A financial adviser can help assess affordability in the wider plan. Reconcile the ledger with bank statements and the eventual shared budget, preserving differences and explanations.