SimplBooks + Lightning Checkout: Bitcoin for e-residents | payinbtc.me

SimplBooks is Estonian accounting software with more than 20,000 users, built around the things an Estonian company actually has to do: sales and purchase invoices, e-invoices sent machine-to-machine to the Tax and Customs Board, VAT returns with their INF annexes, and automatic bank feeds from Swedbank, SEB, Coop and LHV. It runs in Estonian, English and Russian, with a Finnish version as well, and prices start at 9.90 euros a month. For a one-person OÜ it is often the only piece of back office software in use.

A large share of those companies are not run from Estonia. The e-Residency programme passed 142,000 e-residents and more than 43,000 companies founded by them as of July 2026, and e-residents set up a record 5,500 companies during 2025. The owner is a consultant in Lisbon, a developer in Bali, a designer moving every few months. The company is Estonian. The bookkeeping is Estonian. The clients, the bank the client sends from, and the person sending the invoice are not.

That is where the invoice stops being a formality. SimplBooks will produce a correct invoice and file the VAT, but the payment still has to cross whatever sits between a client in Singapore or Sao Paulo and an account at LHV. A SWIFT transfer takes days, costs both sides something, and passes through a correspondent bank that answers to nobody you can call. A card gateway wants a merchant account tied to a jurisdiction and takes a percentage. Neither of them cares that you are two time zones from your accountant and six from your client.

Lightning Checkout is a Bitcoin payment provider founded in 2022 and registered in Estonia, the same jurisdiction as SimplBooks and as BTC2B Group OÜ, the company behind PayInBTC.me. In fact Lightning Checkout is part of the BTC2B Group. It settles over the Lightning Network for smaller amounts and on-chain for larger ones, and says plainly that it has no control over the Bitcoin sent at any point. PayInBTC.me connects it to SimplBooks: your invoices carry a Bitcoin payment link, the amount converts at the moment your client opens it, and the payment lands in a wallet you hold. We run this exact combination on our own books.

Why SimplBooks and Lightning Checkout fit a location-independent company

The bookkeeping is anchored in Estonia. The money should not have to be.

SimplBooks connects to Swedbank, SEB, Coop and LHV. That is the right list for an Estonian company, and it is also a dependency: an owner living in Buenos Aires still needs an Estonian banking relationship in the middle of every payment, subject to its onboarding, its reviews and its hours. Bitcoin does not remove your bank, and you will still want one. It does mean that for the invoices where you offer it, getting paid no longer depends on a bank in a country you may not have visited this year.

One payment method that works the same from every address

Most payment options carry a residency question somewhere in the signup. Card gateways ask where the business banks and where the director lives, and transfer services ask your client to open an account and fund it. A Lightning address asks nothing. It is a string you can use from a phone in Chiang Mai as easily as from a desk in Tallinn, and it does not change when you do. For someone whose whole operating model is being able to move, that property is worth more than a fee comparison.

Time zones and weekends stop being part of the invoice terms

A client approving an invoice at 6pm their Friday means a wire that starts moving Monday and arrives Wednesday, if the correspondent chain behaves. A Lightning payment on that same Friday evening clears in seconds. When your working week is a different week from your client's, the difference between settlement in seconds and settlement in banking days is the difference between a clean cash position and a spreadsheet of things that are probably fine.

The stack we use on our own books

BTC2B Group OÜ keeps its accounts in SimplBooks and collects Bitcoin payments through PayInBTC.me into Lightning Checkout. That is not a claim about the pairing being better than the other thirteen. It means the setup, the read-only connection, the reconciliation habit and the monthly fee invoice are all things we deal with ourselves every month rather than only support for other people.

How the integration works

Setup takes about five minutes and needs no crypto knowledge beyond having somewhere to receive Bitcoin. Everything after that runs on its own, from wherever you happen to be.

Create your Lightning Checkout account

Register with Lightning Checkout and give them the Lightning address you want payments to arrive at, which looks like an email address and comes from any Lightning wallet. If your invoices regularly exceed a few hundred euros, add the XPUB of an on-chain wallet so larger payments settle there, which can be a hardware wallet you travel with or one whose seed stays somewhere safer than your carry-on. Lightning Checkout confirms the account by email, typically within a day.

Connect SimplBooks to PayInBTC.me

Sign in to PayInBTC.me, choose SimplBooks, and authorise the connection to your company. The access is read-only: we read the invoice amount, currency, invoice number and client name so the payment page shows the correct total. We cannot create or edit sales invoices, touch your purchase invoices or fixed assets, or reach the VAT returns and e-invoices going to the Tax and Customs Board.

Link your Lightning Checkout account

Add your Lightning Checkout credentials in PayInBTC.me and decide which invoices carry the Bitcoin option. Many owners switch it on only for the clients who asked, then widen it once the first few have gone through.

Invoice from SimplBooks exactly as before

Your invoice numbering, PDF design, currencies, e-invoice routing and VAT treatment all stay as they are, and the Bitcoin payment link travels with the invoice alongside your bank details. Recurring retainer invoices work the same way. Clients who prefer a transfer keep making one, because nothing has been taken away.

Get paid and get notified

Your client opens the link, sees the invoice total converted to Bitcoin at that moment's rate, and pays by scanning a QR code from any wallet. Lightning payments clear in seconds, at any hour. Lightning Checkout passes the Bitcoin to your address, and PayInBTC.me emails you when it lands so you can mark the invoice paid in SimplBooks.

What an e-resident company gets from this pairing

Getting paid does not depend on where you are

A Lightning address works identically from any country and any network. There is no re-verification when you move, no address on file that has to match a utility bill, and no branch that needs to see you. Your invoice terms stop being a function of your current time zone.

Cross-border payments without the correspondent chain

A SWIFT transfer from a client outside the EU can pass through two or three banks, each with its own fee and its own view of how long the transfer should take. A Bitcoin payment goes from your client's wallet to yours. Nobody in between holds it, prices it, or asks what the payment is for.

Bitcoin that stays in your own custody

Lightning payments arrive at your Lightning address and larger on-chain amounts at addresses derived from your XPUB, so Lightning Checkout can generate them without ever holding your keys. For a company whose owner is rarely in the same country as its registration, an asset nobody else can freeze is a meaningful thing to be paid in.

A flat fee, never a share of your revenue

PayInBTC.me is 1,500 sats per invoice on pay-per-use, or 2,500 sats a month for unlimited invoices, around 1.50 and 2.50 euros. A retainer client billed every month costs the same as a one-off. Nothing scales with the invoice value on our side.

Everything SimplBooks does for you keeps working

E-invoices to the Tax and Customs Board, VAT returns and their annexes, TSD and VD reports, bank feeds, fixed assets, projects and the salary module all continue untouched. The connection is read-only, so Bitcoin is added next to your existing payment details rather than in place of anything.

Revenue you can keep in Bitcoin without an exchange step

If you already convert part of what you earn into Bitcoin, being paid in it directly removes the exchange account, its verification and its fees from the loop. Whether that suits your company is a question about your own risk tolerance and your accountant's advice, not one we will answer for you.

What it costs on a typical invoice

Take a 1,200 euro monthly retainer invoice sent from an Estonian OÜ to a client outside the EU, which is close to the median case for an e-resident consultancy. Costs vary by bank and by country, so treat these as the shape of the comparison rather than a quote.

Method	Cost on a €1,200 invoice	Notes
International bank transfer to your Estonian account	About €15 to €45	The sending bank's fee, any correspondent charges, and the FX spread on conversion, typically one to five business days
Card gateway on the invoice	About €40	Around 2.9% plus a fixed amount, with additional surcharges when the card is issued abroad or the currency differs, and a merchant account tied to a jurisdiction
Transfer service such as Wise	About €5 to €12	A conversion fee in the region of 0.4% to 0.6%, and your client has to hold or open an account with the service to send it
Bitcoin via PayInBTC.me and Lightning Checkout	About €6.50	Lightning Checkout's 1% percentage capped at 5,000 sats of maximum cost each month, roughly €5, plus a flat 1,500 sats to PayInBTC.me, roughly €1.50, settling within seconds. Lightning Checkout becomes 'free' from a monthy transaction total of 500 EUR

On price alone, Bitcoin and a transfer service land in the same range, and it would be dishonest to claim otherwise. The difference is in the third column. The transfer service needs your client to hold an account with it, the card gateway needs your business to be eligible in a jurisdiction, and the bank transfer needs a chain of institutions to be open. The Bitcoin payment needs a wallet and an internet connection, on either end, on a Sunday, from any country. For a company whose owner moves and whose clients are scattered, that is usually the deciding property rather than the few euros.

Who this fits

E-resident consultants running an OÜ from abroad

One-person companies invoicing a handful of clients a month from wherever the owner currently lives. SimplBooks handles the Estonian side and the VAT return, and the payment method needs to survive the owner changing country twice a year. Bitcoin does that without a re-verification email.

Small Estonian software and design studios billing outside the EU

Teams of three to ten invoicing clients in the US, the UK and Asia, where every payment currently means a transfer that clears somewhere between Tuesday and never. Offering a Bitcoin option to the clients who want it takes those invoices out of the queue entirely.

Freelancers on recurring retainers

The same invoice, the same amount, every month. A per-invoice percentage compounds quietly across a year of them, and a capped fee does not. The recurring invoices SimplBooks already generates carry the Bitcoin link automatically once it is switched on.

Bitcoin-native companies keeping part of their treasury in BTC

Businesses that have already decided to hold Bitcoin and would rather be paid in it than buy it afterwards. Payments land in a wallet you control, with no exchange account, no withdrawal limit and no processor balance sitting between the invoice and the coins. Our own company is one of these.

Getting started

You need a SimplBooks account and a Lightning Checkout account. Lightning Checkout asks for a Lightning address at signup, plus an XPUB if you expect payments above a few hundred euros, and confirms by email. PayInBTC.me does the rest.

Register with Lightning Checkout, give them the Lightning address payments should arrive at, and add an on-chain XPUB for larger invoices.
Create your PayInBTC.me account and authorise the read-only connection to your SimplBooks company.
Add your Lightning Checkout details, switch the Bitcoin option on for the clients who want it, and send one invoice as a test before you offer it more widely.

The first month is free, so you can put real retainer invoices through the setup before deciding whether it stays. Full setup instructions are at docs.payinbtc.me.

Get started free →

Frequently Asked Questions

Does this change how I create invoices in SimplBooks?

No. You issue sales invoices in SimplBooks the way you do now, with the same numbering, PDF design, currencies and VAT treatment, and recurring invoices keep running on their schedule. PayInBTC.me adds a Bitcoin payment link to the invoices you choose, next to your bank details. Our connection is read-only, so nothing inside SimplBooks is written to or changed by us.

I run an Estonian OÜ but I do not live in Estonia. Does this still work?

That is the case this pairing is built around. SimplBooks does not care where you log in from, and a Bitcoin payment has no country list on the paying side: your client can settle a euro invoice from anywhere with an internet connection, with no correspondent bank deciding whether it goes through. The one thing that does depend on jurisdiction is your own provider account, so check Lightning Checkout's terms for the country your company is registered in and, if relevant, where you are resident.

Does my client pay over Lightning or on-chain?

Lightning Checkout chooses based on the amount. Smaller invoices, up to a few hundred euros, go over the Lightning Network and settle within seconds for a fee measured in cents. Larger amounts go on-chain, where confirmation takes longer but the cost works out better. Your client sees a single payment page and QR code either way, and can pay from any Bitcoin wallet.

Where does the Bitcoin end up while I am travelling?

In your own wallet. Lightning payments arrive at the Lightning address you registered with Lightning Checkout, and on-chain payments go to addresses derived from an XPUB you provide, which lets addresses be generated without anyone else holding your keys. Many owners point the XPUB at a hardware wallet whose seed is stored somewhere other than their luggage. Lightning Checkout states it has no control over the Bitcoin sent, and PayInBTC.me never touches funds.

What does Lightning Checkout charge, and what does PayInBTC.me cost per invoice?

PayInBTC.me is 1,500 sats per invoice on pay-per-use, about 1.50 euros, or 2,500 sats a month for unlimited invoices, about 2.50 euros, or 25,000 sats a year. The first month is free, with three free invoices on the pay-per-use plan. Lightning Checkout charges 1% per transaction with a monthly maximum fee of 5,000 sats and advertises no contract or cancellation period.

Will SimplBooks mark the invoice as paid automatically?

Not today. Our connection is read-only, so we cannot write a payment into your books. You get an email the moment the Bitcoin clears and you mark the invoice paid in SimplBooks yourself, exactly as you would for a transfer that arrived outside your bank feed. Automatic reconciliation is on our roadmap and we will not describe it as available before it is.

How do I account for a Bitcoin payment in Estonian bookkeeping?

The invoice itself does not change. The amount, the currency and the VAT stay as SimplBooks recorded them, and your e-invoice and VAT return to the Tax and Customs Board are unaffected, because Bitcoin is only how the client settled a euro invoice. What needs a decision is how you record the Bitcoin you now hold and what happens when its value moves. That is a question for your accountant, and Estonian treatment has changed over time, so take current advice rather than ours.

What if a client does not want to pay in Bitcoin?

Then they pay the way they always have. The Bitcoin link sits alongside your bank details rather than replacing them, and no client is prompted to do anything differently unless they choose the link. For the ones who do want it, the payment is scanning a QR code and confirming in their wallet, which takes less effort than setting up a new international transfer.

More questions? See our full FAQ →

Accept Bitcoin on SimplBooks Invoices with Lightning Checkout