Bitcoin and ether exchange startup Coinbase is planning to shift the cost of certain kinds of transaction fees to users later this month.

In a new blog post, the startup cited its subsidization of so-called ‘on-chain’ transaction fees, noting that it has long paid the cost the network requires to confirm these transfers.

Yet, Coinbase said that this policy has now “become a significant cost” and that fees will shift to users looking to send network transactions over the bitcoin and ethereum blockchains beginning 21st March.

Transactions on-site between users will continue to be provided at no cost, the startup added.

Instead, fee amounts will be given when a user is preparing to issue a transaction, according to the firm.

Coinbase product manager Ankur Nandwani wrote in the blog post:

“Fees will be assigned dynamically based on the current network conditions and will be paid by customers when they send an on-chain transaction.”

The startup outlined other pending service changes in the post, including the shutdown of a feature that enables account access by way of SMS.

Coinbase said that the feature, which dates back to 2013, was more relevant in days before widespread smartphone use, and that it is shifting away from the service in favor of its mobile-based apps. The SMS tool will be taken offline on 21st March.

Coinbase is also shutting down a user payment page feature launched in mid-2014, also citing the growth of its mobile app as an alternative.

Disclosure: CoinDesk is a subsidiary of Digital Currency Group, which has an ownership stake in Coinbase.

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