Gas sponsorship: trace who funds the paymaster
A sponsored transaction can be free to its user while still consuming a sponsor’s funds. For account-abstraction research, measure the paymaster’s funding and actual charges before calling the activity economically self-supporting. An operation count alone cannot show who ultimately bears the cost.
ERC-4337 distinguishes the paymaster deposit used for gas charges from its locked stake. The worksheet follows that distinction. Contract versions and deployed EntryPoints matter; the presence of a paymaster field does not prove that all fees or all operations are subsidized identically.
Reconcile the deposit before estimating runway
Choose the network, EntryPoint deployment, paymaster address and block interval. Read opening and closing gas deposits at matching blocks. List deposit top-ups, withdrawals and actual operation charges. Reconcile opening deposit plus top-ups minus withdrawals minus charges to the closing deposit.
Do not use the paymaster contract’s ordinary native-token balance as a substitute for its EntryPoint deposit. Funds at another address or in a locked stake may require different actions before they can pay operation costs. Treat external replenishment promises as separate evidence rather than immediately available funds.
For each covered operation, retain actual gas cost, sponsor identity and execution outcome. Maximum prefunding is a capacity check, not necessarily the final expense. Refund and penalty behavior depends on the implemented version. Prefer finalized actual charges when measuring historical spend, while using a disclosed conservative reserve for forward capacity scenarios.
Hypothetical sponsorship ledger
Assume a fictional paymaster starts with 12 ETH deposited. During a seven-day window it receives 5 ETH of top-ups, withdraws 1 ETH and incurs 7 ETH of actual charges. The closing deposit is 12 + 5 − 1 − 7 = 9 ETH.
| Ledger item | Hypothetical ETH |
|---|---|
| Opening gas deposit | 12 |
| Top-ups | +5 |
| Withdrawal | −1 |
| Actual operation charges | −7 |
| Closing gas deposit | 9 |
At an assumed continuing charge rate of 1 ETH per day, a mechanical gross runway is nine days without replenishment. If the operator keeps a 2 ETH minimum buffer, the corresponding usable amount is 7 ETH and the scenario runway is seven days. Neither calculation promises operations will remain accepted for that long.
Suppose the seven days contain 10,000 charged operations, including 1,000 whose intended application execution reverts. The average is 0.0007 ETH per charged operation and about 0.0007778 ETH per successful operation if the remaining 9,000 each satisfy the stated success rule. Failed execution can still cost the sponsor; user-visible failure is not evidence of zero expense.
Separate subsidy from reimbursement
A paymaster may later collect tokens, subscription payments or other reimbursement. Measure those receipts separately, including collection time, asset identity and conversion assumptions. A nominal reimbursement claim is not the same as spendable ETH credited to the gas deposit.
Report gross sponsorship cost, actual reimbursements and net external funding requirement. If a sponsor receives 3 ETH-equivalent of tokens but cannot establish a conversion path, keep that amount in a separate category. Do not subtract it as though it had already replenished the deposit at a guaranteed rate.
Use stress scenarios for gas prices and activity volume without forecasting either. An increase in successful usage can shorten funding runway, while a restrictive sponsorship policy can reduce charges by rejecting operations. Lower spend alone does not establish healthier adoption.
The final note should link operation coverage to deposit movements and clearly label future replenishment as conditional. Recheck when eligibility policy, EntryPoint version, funding source or reimbursement terms change. The analysis describes who funds usage and what the observed deposit can support under assumptions; it does not judge user demand from subsidy counts.
A runway ratio also needs a policy boundary. If sponsorship stops once a deposit falls below a threshold, the practical cutoff can precede depletion. Separate eligibility failures from insufficient funding and from application reverts. They can all reduce completed actions, but only the last category necessarily refers to an operation that reached application execution in the observed dataset.
FAQ
Does “gasless” mean nobody pays network costs?
No. A sponsor or another party may pay, or later recover costs. Trace the actual payment and reimbursement paths.
Can locked paymaster stake be counted as immediate gas funding?
Not automatically. ERC-4337 distinguishes stake from the gas deposit. Verify access and timing before including either in available funding.