Do Merged-Mining Rewards Carry an Extra Pool Fee?
There is no single industry-wide answer to this question, because fee treatment is determined by each pool's published rules rather than by a technical requirement of merged mining itself. A pool may apply its standard fee to auxiliary rewards, apply a different fee specific to the auxiliary coin, or embed the auxiliary reward inside a payout calculation that already nets out fees before display.
This makes it necessary to separate two concepts that are often conflated:
- Pool fee — the percentage the pool retains under its published fee schedule for a given reward stream.
- Payout method — the rule (for example PPS+ or PPLNS) used to allocate rewards among miners and to determine who bears the statistical variance of block discovery.
A payout method is not itself a fee, and PPLNS in particular should not be described as a fee — it is an allocation rule that happens to shift variance toward the miner. Understanding this distinction is a prerequisite for reading any pool's fee page correctly.
What Merged Mining Means for Pool Miners
Merged mining allows a miner to submit proof-of-work that can simultaneously satisfy the requirements of a primary blockchain and one or more auxiliary blockchains that share a compatible hashing algorithm. Sharing a hashing algorithm alone is not sufficient: the auxiliary chain must support the required protocol, and the pool must implement merged mining. AuxPoW (Auxiliary Proof of Work) enables this by allowing the auxiliary chain to verify work committed to its block (Namecoin technical explanation). The technique was first implemented to let Bitcoin miners also produce valid blocks for Namecoin, and it has since been adapted to other algorithm families — most notably Scrypt-based Litecoin and its auxiliary chains such as Dogecoin.
Auxiliary rewards arise on separate blockchains, but how miners receive them depends on the pool's rules. A pool may credit each asset separately, convert rewards, or incorporate their value into a combined payout. To understand the fee treatment, identify each reward source and the rules used to allocate and pay it.
How Payout Methods Affect Merged-Mining Rewards
Under a PPS-type method, the pool pays each valid share a theoretical reward calculated from expected block value, absorbing the risk that an individual block is not actually found or is orphaned. Because the pool assumes this risk, PPS-type fees for the covered component are typically higher than PPLNS fees for the same chain.
Under PPLNS (Pay Per Last N Shares), rewards are only distributed when the pool actually finds a block, and they are allocated according to each miner's share of the pool's total accepted work over a defined rolling window. This ties payouts more directly to the pool's real block-finding outcomes, which introduces more short-term variance for the miner in exchange for typically lower fees.
A practical consequence for merged mining is that the payout method selected for the primary coin does not automatically apply to the auxiliary coin. On ViaBTC, for example, miners mining LTC may choose either PPS+ or PPLNS for their LTC rewards, but the documentation for LTC's currently supported merged-mining coins (DOGE, BELLS, PEP, and DINGO) states that these auxiliary rewards are distributed under PPLNS regardless of which payout mode is selected for LTC (ViaBTC LTC Merged Mining Tutorial). A miner who selects PPS+ for more predictable LTC payouts will still see DOGE-denominated rewards vary with the pool's actual block discoveries on the Dogecoin chain and the miner's share of eligible work during the PPLNS window.
The practical takeaway is that a pool's headline payout label describes the primary coin, not necessarily every reward stream the miner receives. Each auxiliary coin's payout treatment should be checked separately.
How ViaBTC Structures Merged-Mining Rewards
ViaBTC's current pricing page lists the following published fee structure for its BTC pool (ViaBTC Pricing):
| BTC payment treatment | Published fee | BTC reward component |
|---|---|---|
| PPS+ block reward | 4% | Block subsidy, paid on a PPS basis |
| PPS+ transaction fees | 2% | Transaction fees, distributed under PPLNS |
| PPLNS | 2% | Block reward and transaction fees, both allocated under PPLNS |
These figures describe distinct reward components, not a combined rate. Under ViaBTC's PPS+ structure, the block-reward portion is paid at a theoretical PPS rate subject to a 4% fee, while the transaction-fee portion of the same block is separately distributed under PPLNS and subject to a 2% fee. Adding the two percentages together would misrepresent the fee schedule, since they apply to different parts of the reward rather than to the same value.
ViaBTC's pricing page also states that PPLNS allocation is based on a miner's share of pool work over the last five difficulty rounds, and that rewards are settled once six block confirmations have passed. These are the parameters shown for the main-coin reward components above. They do not establish the accounting window or confirmation requirements for each merged-mined coin.
Regarding merged mining specifically, ViaBTC's support documentation states that LTC miners can receive merged-mining rewards in DOGE, BELLS, PEP, and DINGO, and that these auxiliary rewards are settled to the miner's account approximately every two hours under PPLNS (according to the LTC merged-mining tutorial, updated September 15, 2026). Separately, ViaBTC's general merged-mining explainer describes BTC miners as able to receive NMC and FB rewards under the same principle — using the same submitted proof-of-work to earn rewards on a compatible auxiliary chain without needing separate mining hardware (What Is Merged Mining? – ViaBTC Support). Supported coin pairs and settlement parameters are product details that can change, so readers should confirm the current list on the pool's live documentation rather than treat any list as permanent.
The tutorial confirms the LTC auxiliary coins' PPLNS distribution and two-hour settlement schedule, but does not separately state their fee percentages. A PPLNS label alone does not establish that the 2% rate in the BTC table applies to those rewards. Confirm the fee applicable to each auxiliary coin through explicit current terms or ViaBTC support before using a percentage in an earnings comparison.
Merged mining reuses the same hashing work without requiring a separate ASIC or a second full electricity load. That technical benefit does not establish whether an auxiliary reward carries a pool fee. Likewise, the word "free" alone is insufficient to determine the applicable fee, payout conditions, or withdrawal charges.
A Simple Illustration of Net Auxiliary Reward Allocation
The following is a hypothetical, illustrative calculation only. It is not a claimed industry standard and does not represent any specific pool's exact formula, since eligibility rules, share windows, and fee treatment vary by pool and by coin.
A general expression for a PPLNS-style allocation is:
Estimated payout ≈ (miner's eligible work in the payout window ÷ total eligible pool work in that window) × distributable auxiliary reward before pool fees × (1 − applicable pool fee)
Here, eligible work means accepted work measured on a consistent difficulty basis. If shares have different difficulties, use difficulty-weighted shares rather than raw share counts. The reward base must be before the applicable pool fee; if it is already net of that fee, do not deduct it again.
Suppose the distributable auxiliary-chain reward for a given block, before pool fees, is 1,000 units, a miner's qualifying share of pool work during the relevant window is 0.50%, and the hypothetical pool fee for that reward stream is 2%. This assumed rate is not a confirmed ViaBTC auxiliary-coin fee. Then:
1,000 × 0.005 × (1 − 0.02) = 4.9
The miner's estimated credited amount would be 4.9 units, before any separate conversion or withdrawal costs are applied. This figure is a labeled hypothetical used to demonstrate the mechanics of the calculation, not a projection of expected earnings from any specific pool or coin pair.
Pool Fee Versus Other Costs That Affect Net Returns
Estimating the real value of merged-mining rewards requires keeping several distinct cost categories separate, since blending them can lead to double-counting.
| Item | Description | Is it a pool fee? |
|---|---|---|
| Pool mining fee | Percentage retained by the pool under its published schedule | Yes, when applicable to that reward stream |
| Payout-method variance | Statistical variance inherent to PPS+ or PPLNS allocation | No — a feature of the payout method, not a charge |
| Rejected or stale shares | Submitted work not credited under the pool's rules | No — reduces credited work, not a fee |
| Electricity cost | Cost of powering mining hardware and site infrastructure | No — an operating cost |
| Hosting fee | Charge paid to a hosting provider, where applicable | No |
| Conversion spread or trading fee | Cost of exchanging an auxiliary asset for BTC or another currency | No — a separate market cost |
| Withdrawal fee | Network or platform charge for moving funds out of the pool | No — separate from the pool mining fee |
Keeping these categories distinct prevents a common error: treating a reward figure that is already displayed net of the pool fee as though the fee still needs to be subtracted again, or conversely, ignoring conversion and withdrawal costs that are not reflected in the pool's displayed balance.
What to Check Before Comparing Merged-Mining Pools
Because fee structures and payout treatment vary by pool and can change over time, a useful comparison should verify, for each supported coin pair:
- Which parent and auxiliary chains are currently supported.
- The payout method used for the primary coin, and separately, the payout method used for each auxiliary coin.
- The published pool fee applicable to each reward component.
- The eligible-share window and confirmation requirements before rewards are settled.
- Settlement frequency to the pool account, as distinct from withdrawal timing.
- Minimum withdrawal thresholds and any withdrawal or network fees.
- Conversion costs, if the miner intends to exchange the auxiliary asset for another currency.
This checklist is a starting point for evaluation rather than a fixed procedure, since not every factor will be relevant to every miner's setup.
Conclusion
Merged mining allows the same submitted proof-of-work to qualify for rewards on more than one chain, but it does not standardize how those rewards are priced or paid out. A pool's headline fee percentage typically describes one reward component under one payout method; auxiliary-chain rewards may follow a different rule entirely, as seen in ViaBTC's treatment of LTC merged-mining coins under PPLNS regardless of the primary payout mode selected. The more useful comparison for a miner is not the number of additional coins advertised, but the net expected value after accounting for the specific pool fee, payout method, settlement timing, and any conversion or withdrawal costs that apply to each individual reward stream. Reviewing a pool's current, published documentation for each supported coin pair remains the only reliable way to make that comparison.
FAQ
Does merged mining require a separate ASIC or extra electricity?
No. Merged mining uses the same proof-of-work submitted for the primary chain to also qualify for rewards on a compatible auxiliary chain, so it does not require additional mining hardware or a separate electricity load for the auxiliary reward itself.
Is ViaBTC's PPS+ fee 6% when you add the block-reward and transaction-fee percentages?
No. The 4% and 2% figures apply to two different components of the block reward — the block subsidy and the transaction fees — which are calculated and paid under different rules. They should not be summed into a single combined rate.
If I select PPS+ for my primary coin, will my merged-mining rewards also be paid as PPS+?
Not necessarily. On ViaBTC, for example, LTC miners can select PPS+ or PPLNS for LTC, but currently listed LTC merged-mining coins (DOGE, BELLS, PEP, DINGO) are distributed under PPLNS regardless of that selection. Each coin's payout treatment should be checked individually.
Are merged-mining rewards free of pool fees?
The answer depends on the pool and reward stream. Reusing the same hashing work does not establish whether a pool fee applies, and a PPLNS label does not establish the fee percentage. Check terms that explicitly cover the auxiliary coin; if the fee scope is unclear, confirm it with the pool before calculating net rewards.
Why might my auxiliary coin balance take time to appear?
Auxiliary rewards are generally settled to a pool account on a set schedule (for example, ViaBTC currently settles certain LTC merged-mining coins roughly every two hours) and may also be subject to block-confirmation requirements before being credited. This settlement timing is separate from the process of withdrawing funds to an external wallet.
References
- ViaBTC. "Fees."
- ViaBTC Support. "What is Merged Mining?"
- ViaBTC Support. "LTC Merged Mining Coins Mining Tutorial."
- Namecoin. "Electrum-NMC: AuxPoW Deserialization." July 1, 2018.