How can I pay if I don’t already have some bitcoin?

The easiest way.

Install the Strike app on your android phone, iPhone, or on your browser as a chrome extension. You will need to complete some basic KYC (Know Your Customer) info such as your full name, your address, as well as upload a picture of a photo ID. Once you are signed up and your identity has been verified by Strike, you can link your bank account or debit card and deposit funds into your account. You are now equipped to send bitcoin to anyone in the world, instantaneously, even if the other person doesn’t have a Strike account!

Here’s how it works.

Say that after our tutoring session, you owe me 0.001 BTC = 100,000 sats (satoshis—the smallest unit of bitcoin, which is 10^-8 BTC). You let me know that you are signed up with Strike, and therefore have the ability to send lightning network payments. I will generate an invoice for 100,000 sats using my own lightning network node and share either a QR code or a text invoice, depending on your preference. If you have Strike installed on your phone, I recommend the QR code. I will screen share the QR code and you can easily scan it directly from the Strike app. The amount and the destination are automatically included in the payment invoice, so all you have to do is hit “confirm payment.” That’s it! The payment should be effectively instant, and the fee no more than 1 cent.

One quirk is that the amount of USD that Strike requires to fulfill the payment depends on both the number of satoshis that my payment invoice is for, as well as the current price of bitcoin as determined by Strike. If you need to top up your USD balance on Strike to complete the payment, I recommend depositing a few percentage points more in fiat than what I am charging you for to ensure that the payment goes through. For example, if I charge you $20 for our session, it is unlikely that Strike will quote you exactly $20 for the USD amount of the payment on your end. More than likely there will be a small deviation, such as $19.97 or $20.04. To account for this possibility, I would recommend you deposit something like $20.50 before scanning the payment invoice.

It’s not my intention to extract more value (in USD terms) than was agreed upon, and do keep in mind that it can certainly happen that you end up paying me less (in USD terms) if the price of bitcoin falls. I’m not concerned about the USD value, just the number of satoshis. If you like, we can fix the price of bitcoin at any point during our tutoring session. For example, if you literally only have $20 to pay for tutoring and can’t afford to pay even a penny more, we can determine the number of satoshis you must send me at the beginning of the meeting before we even begin so that Strike will for sure be able to complete the payment for you at the end of our session.

Slightly less elegant solution.

You can use CashApp, Kraken, or any other app/exchange that has enabled lightning withdrawals. However, you first need to have bitcoin available to send it. This means, for example, that if you owe me 100,000 sats, you first need to buy 100,000 sats (or slightly more, depending on withdrawal and transaction fees of the exchange). Once that transaction is complete, you can pay the 100,000 sats invoice by scanning the QR code/copy-pasting the invoice I send you.

Even less elegant solution.

You can send bitcoin on-chain from other cryptocurrency exchanges which have yet to enable lightning payments. Some examples: Coinbase, Gemini, Binance, etc. You will first need to sign up on the exchange and buy bitcoin. In many cases you will need to wait 5-7 days after you purchase bitcoin to be able to withdraw it in order to allow your fiat payment to clear. Beware that most of these exchanges charge exorbitant fees to send bitcoin. Binance for example charges a flat 0.0005 BTC fee to withdraw, which at $20,000 per bitcoin equates to $10. Strike will allow you to withdraw bitcoin on-chain from a bitcoin balance with no fee, so it can also be an option. But for my tutoring payments, I would always suggest lightning payments as they are faster and more anonymous for you (the sender).

Can’t I just pay you with a credit card or Venmo?

Many consumers don’t realize that credit card payments are not free! In fact, to accept US credit cards on this site would cost me 2.9% + a flat $0.30 fee. As a merchant, Venmo would charge me a similar 1.9% + $0.10 fee. Moreover, if a non-US resident wanted me to tutor them, the international transaction fees would make the situation even worse. Why should I be limited to tutoring US residents? As long as you speak English, we can help each other out from anywhere in the world without asking anyone else for permission. Not to mention that, as your math tutor, I don’t want or need to know your address, full name, or any other personal details. I just need a name to refer to you by during our tutoring session. Credit cards and fiat payment apps like Venmo are financial intermediaries that get between me and you, the tutor and the student, and create needless friction in what should be a seamless transaction: my time and knowledge for your money.