Tried to use my girlfriend CPF

You can say that you don`t have or remember your CPF, pay and walk out. Unless they give you a discount or something like that I wouldn't bother much.

@NewBrazil

Possibly because her CPF is irregular, due to non-payment of taxes, did not vote or similar?

You can say that you don`t have or remember your CPF, pay and walk out. Unless they give you a discount or something like that I wouldn't bother much. - @martinsan

You MUST give a CPF number for any purchases over R$1000, under that value it is optional. However you can always ask to split the payment into 2 or more parts - eg R$1500, ask to pay R$900 followed immediately by R$600.

Here in PB purchases over R$500 require addition of one's CPF as of May 2:

https://www.sefaz.pb.gov.br/9-posts/417 … -paraiba#:

Often, at the supermarket,we use my wife's CPF and I pay. There never seems to be a problem of me purchasing on herCPF but that may just be supermarket-specific.

As for online purchases, I think a CPF number is almost always required.

One can check their CPF for irregularities here:

https://servicos.receita.fazenda.gov.br … ublica.asp

11/28/25 Interesting that Pernambuco and (soon) Paraíba are requiring CPF on purchases of relatively low value.  Here in Amazonas it's not required so far, and I never give it when asked.  I'm not sure why anyone would want to:  I doubt very much that any agencies are tracking our purchases, but if any ever want to, that would be the way.  My experience with online purchases is that it is required, as @mberigan wrote. At pharmacies I get the discounts to which I'm entitled, but ask them not to put my CPF on the NF.

Amazonas does give a rebate on the ISS (Imposto Sobre Serviços) to consumers whose CPFs show high enough payments of ICMS as captured on Notas Fiscais, but we've never paid enough ISS to justify either the recordkeeping or the loss of privacy.

I heard that an irregular CPF can block you from doing certain financial transactions, not sure what in detail. Not long ago, I was trying to setup my FGTS account at the Caixa, and they didn't let me proceed because to my surprise my CPF was irregular (thanks to my girlfriend for filing the tax return for the wrong year).

(translated from a SERASA page)

*Benefits for the State*

The practice of requesting the CPF (Brazilian taxpayer ID) on the invoice strengthens the fight against tax evasion and promotes greater transparency in the tax system.

With the information recorded, public agencies can more accurately monitor commercial transactions and ensure that taxes are collected.

*Benefits for those who issue the invoice*

For the merchant, suggesting to the customer that they include their CPF on the invoice demonstrates a commitment to legality and transparency.

In addition, complying with tax obligations reinforces the company's credibility and helps build a more professional image in the market.

(Source: https://www.serasa.com.br/blog/cpf-na-nota-fiscal/)

On the street people here are saying (complaining?) that it is all about the gov't trying to stop tax avoidance (evasion?) which IS a huge problem here. I know of many health professionals that offer their services with two forms of payment: with an official receipt (on the books) or without a receipt. Initially it was a cash transaction that would keep transactions off of the books but PIX came along and that SEEMED to be a method that made it hard for the RECEITA FEDERAL (IRS) to track but the RF has improved their tracking, especially of PIX transactions and people [here] are starting to move back to cash. And I didn't mean to pick on health professionals because here I see E-V-E-R-Y-B-O-D-Y doing tax avoidance (both buyers and sellers). It seems that it is pretty common for people at all income levels to have unreported income streams and the RF is starting to improve comparing the numbers and catching those not paying their "fair share."