Quote from: ecsqatar on July 05, 2017, 05:58:43 PM

If you read HCP post ,he told me i will be charged once 0.01BTC for 100 transactions ,and rest 99 transactions will be free ,they charge me 0.01BTC on first transaction and on second transaction again charged me 0.000613 as mining charges.So it is very confusing for me .

Sorry... perhaps I was not clear... you have created a "2FA" (Two Factor Authentication) wallet in Electrum. This involves using the services of a Third Party Service (TrustedCoin) who provide the 2FA functionality. They charge per transaction to provide the 2FA service.

These 2FA charges are in addition to the normal Bitcoin network transaction fee (aka miners fee).

You were not charged by TrustedCoin in your second transaction. That 0.000613 is the network transaction fee ("miners fee"). All bitcoin transactions incur a network transaction fee. This is the fee that gets paid to miners as a "reward" for including your transaction in a block. https://en.bitcoin.it/wiki/Transaction_fees (note, this information may be a little out of date). This fee is payable regardless of any other service fees you might be paying (ie. 2FA, or withdrawl fee from exchange or online web service etc)

The general rules of thumb regarding miners fees are:

Fees are calculated based on your transaction data size. Data size is influenced by the number of inputs and outputs in a transaction. NOTE: The amount of BTC being sent/received is usually irrelevant.
Fees should be caculated on a satoshis/Byte (or BTC/kiloByte) basis
The larger your fee rate, the more likely it is for a miner to include it in a block

Hopefully that clears some things up...