If the government has a lien for taxes for $1,000 and the person has real estate worth $5,000 would everyone agree that the b'chor has a right to "pi sh'naim" on the remaining $4,000 or does the lien go on all $5,000 in which case b'chor is not entitled to anything extra.
Baltimore, maryland USA
A lien because of usual debts does not stop a Bechor from getting Pi Shenayim. The land belongs to the owner until Beis Din gives it to the claimer - but here is different. The Nimukei Yosef (and Tosfos DH Im) explain that all his land is on lien to the king and the king can take it or sell it all at any worth to get his taxes. Plus, all the land in his country is basicly under the king's control.
So if your question is during the Gemara's time, there is no Pi Shenayim at all. But if the government only takes exactly what it deserves, then for the remaining land there is Pi Shenayim. See Pischei Teshuva CM 278:9. And if seizing the land is only a form of collecting debts (and not repossession) then it wouldn't affect Bechor at all.
All the best,