The tax lien secures payment of a specific year or account. That year or account is either priority or general.
The POC may report $5,000 of secured debt, and this secured debt will relate to a specific year. The POC will always assume that the IRS is going to get paid the secured amount.
IRS always applies payments in the way that is in its best interest. Remember that rule, and you understand a great deal about the taxing authority. Let’s say that the taxpayer-debtor has $5,000 of personal property (all exempt, but the IRS doesn’t care, because exemptions don’t apply to it). The debtor owes $15,000 in general tax debts, $25,000 in priority tax debts.
Assuming that the tax lien covers both the general and the priority years, the IRS will take $5,000 of the general unsecured liability and make it secured, and leave the rest the way it is, because it would rather have the security use up general unsecured debt than priority debt, which will still be owed at the end of the day anyway.