Source: https://rivet.global/blog/poland-software-house-us-clients-usd-nbp-rate
Published: 2026-09-17 · Updated: 2026-09-17 · By Rashidatou K.

# Polish software houses with US clients: collecting dollars and handling the NBP rate

How a Polish software house collects from American clients in dollars, why the NBP rate matters for tax, how FX differences arise, and when to convert to zloty.

## Key takeaways

- Polish tax rules convert foreign-currency invoices and payments at the NBP average rate from the last business day before the relevant date.
- The difference between the rate on the invoice date and on the payment date creates a realised FX difference (różnica kursowa) for tax.
- American clients pay faster and in full when they can use ACH to US account details.
- Holding dollars and paying dollar costs from them reduces both conversion costs and the number of FX differences to track.

A Wrocław software house with 40 developers bills three US clients about $150,000 a month. The dollars arrive by international wire into a zloty account, are converted at the bank's rate, and the accountant then books each invoice at one NBP rate, each payment at another, and the conversion at a third. Month end takes two days.

## The NBP rate rule

Polish tax law converts foreign-currency amounts at the National Bank of Poland's average rate (Table A) from the last business day before the relevant date:

- the invoice is booked at the rate from the business day before the invoice or sale date,
- the payment is booked at the rate from the business day before it is received.

For VAT, the rate from the business day before the tax point applies, unless you choose the ECB rate.

## Where FX differences come from

If the dollar falls between invoice and payment, the zloty value received is lower than the zloty value booked. That gap is a realised exchange difference (różnica kursowa): a deductible loss here, taxable income if the dollar rose.

A second difference appears when you sell dollars for zloty at your provider's rate rather than the NBP rate. Good accounting software calculates both; your accountant needs clean data to do it.

## Fewer conversions, fewer differences

Every conversion is an event to book. A software house that converts every dollar payment on arrival, then buys dollars to pay a US contractor or a conference, creates two conversions and two sets of differences where none were needed.

Holding a dollar balance changes the pattern. Client payments arrive and stay in dollars. Dollar costs are paid from them. Zloty conversions happen on a schedule, for example once a month before payroll, at a rate you see first.

## How the clients pay

American clients pay vendors by ACH. A Polish IBAN forces an international wire, which some smaller US companies approve slowly, and which can lose intermediary fees on the way. US account details in the software house's own name let the client pay by ACH like any American vendor, and the amount that arrives matches the invoice.

The client will also ask for a W-8BEN-E. With it, and the Poland-US tax treaty where relevant, payments for services performed in Poland are made without US withholding.

## Paying into Poland: the local rail

| What | Detail |
|---|---|
| Local rail | Express Elixir |
| Run by | Krajowa Izba Rozliczeniowa (KIR) |
| Settlement | Seconds, 24/7, up to PLN 100,000 per transfer |

Source: [KIR: Express Elixir](https://www.kir.pl/). Checked when this guide was last updated; the scheme's own page has the current figures.

## Where Rivet fits

A Rivet business account gives a Polish company US account details in its own name on every plan, for ACH and wires. Payments are matched to invoices, dollars can be held or converted at a rate shown before you confirm, and each statement line carries the rate for your accountant. From the Growth plan, euro and sterling details are added; on Scale, balances in 30 currencies, zloty included. Rivet is not a bank; regulated partner institutions hold the funds.

## Questions

### Which exchange rate does a Polish company use for a dollar invoice?

For income tax, the NBP average rate from the last business day before the invoice date (or the sale date). For VAT, the NBP rate from the business day before the tax point, unless you opt for the ECB rate.

### What is a różnica kursowa?

An exchange difference: the gain or loss from the change in rate between booking a receivable and receiving the payment, both at NBP rates. It is taxable income or a deductible cost.

### Does converting dollars to zloty create another difference?

Selling dollars at the provider's rate rather than the NBP rate also produces a difference. Many companies account for it with the help of their accounting software.

### Should a software house keep dollars?

If it pays contractors, tools or travel in dollars, yes. Converting only what you need in zloty reduces conversions and simplifies the books.