Pesquisando sobre a regra de transição, verifiquei que tanto o Banco Mundial quanto entidades representativas da profissão de atuário utilizam a tradução literal.

Portuguese term (edited): Transição Pedágio 50%

This is how I would explain the term, not translate it because in my view it's untranslatable.

Brazilian legalese can be tedious, atrocious, nonsensical, and this seems to be a good (or bad?) example. What does "pedágio" have to do with the usual meaning of the word? Absolutely nothing, except the notion of gaining access to something; in this case, the full retirement benefits or pension. The closest I got to a "definition" was the following (which still leaves a lot to be desired; as we say it in PT-Br "falou, falou e não disse nada"):

Como você deve ter percebido, existe a palavra “pedágio”.

Quando falamos desta Regra de Transição, a pessoa paga como se fosse um imposto, em tempo de contribuição, para conseguir a sua tão sonhada aposentadoria.

Isto é, a pessoa contribui por um pouco mais de tempo para ter acesso ao benefício. (emphasis added)

https://ingracio.adv.br/regra-de-transicao-pedagio-50/

It's not "como se fosse um imposto" (as if it were a tax). It is a form of TAXATION in the sense that it's not optional. The surcharge/tax (whatever you want to call it) was IMPOSED upon the workers; they have no choice: either work a few more years or pay this tax if they want to retire. This was part of the post-coup labor reform ("reforma trabalhista") that was presented to the working class as something that was supposed to be beneficial. The disastrous results are showing in today's labor market.

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Note added at 4 hrs (2022-03-29 20:44:41 GMT)
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On the subject of real "pedágios" (toll fees), also another form of imposition:

As a "paulista", I can't help but think of the many times I heard residents of my home state (São Paulo) brag about the wonderful highways/roads throughout the state, which are maintained by the myriad of "pedágios" all over. When I tell my F&F that in over 30 years living in the United States, I was charged highway toll just once (in Florida), they have a hard time believing it. This contrasts sharply with the 8-10 toll fees that drivers have to pay on a 500-mile stretch in SP. And mind you, the freeways here (in Arizona) are better than those in São Paulo state!

Portuguese term (edited): Transição do Pedágio 50%

- to avoid a nasty surprise on the curtailed amount of contingent pension benefits becoming vested ('accessed'): query in favo(u)r inhabitants of the favelas.....

I considered tax grossing-up, a

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Note added at 20 hrs (2022-03-30 12:52:18 GMT)
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tax grossing-up .... a UK Capital Ttransfer Tax of old / present-day Inheritance Tax (also known in 'my day' - and by dinosaur English accountants who shall remain nameless - as Estate or Death Duty) scamming of a donor, rather than the donee of a generous gift.