After the online application and fee, USCIS issues instructions, and supporting documents are submitted with Form I-140G through the official portal. Keep the payment confirmation and any reference number with the case file. Wait for those instructions rather than assembling a speculative package, because the request defines what is actually needed.
Keep a payment record that stands alone
Save the confirmation screen, the receipt, the date, the account debited, and the exact amount, for every person included. Households that pay several fees in one sitting can later struggle to show which payment belonged to which applicant. Store these alongside the application copy rather than in an email folder.
If a question arises months afterwards about whether a fee was paid, a complete contemporaneous record answers it in minutes. Create the payment record on the day of payment rather than reconstructing it later. Capture the confirmation screen, the receipt or reference number, the exact amount, the account debited, and the name of the individual the payment covers, and store the set with the application copy rather than in an email folder.
Households paying several fees in one sitting are the ones most likely to lose track of which payment belonged to whom. After payment, wait for the official instructions before assembling documents, since the request defines what is needed and a speculative package usually has to be redone. Keep passports and civil records current in the meantime, because a wait can outlast their validity.