Muszę opłacić rachunki.

Muszę is the 1st person singular form of the verb musieć.

So:

• musieć = to have to / must
• muszę = I have to / I must

In everyday English, it can often match:

• I have to
• I need to
• I must

The ending -ę tells you the subject is I.

Because Polish usually drops subject pronouns when the verb already makes the subject clear.

• Muszę already means I have to
• So Ja muszę opłacić rachunki is possible, but ja is usually only added for emphasis or contrast

For example:

• Ja muszę opłacić rachunki, nie ty.
  I have to pay the bills, not you.

Without emphasis, Muszę opłacić rachunki is the most natural version.

Because after musieć, Polish normally uses an infinitive, just like English uses must + verb or have to + verb.

Structure:

• muszę = I have to
• opłacić = to pay / to settle
• rachunki = bills

So the pattern is:

muszę + infinitive + object

That is directly parallel to English:

• I have to pay the bills

This is a very common question, because Polish uses aspect and also has several related verbs for pay.

1. płacić

This is imperfective.

It usually means:

• to pay
• to be paying
• to pay regularly / habitually

Examples:

• Płacę rachunki co miesiąc. = I pay bills every month.
• Płacę kartą. = I’m paying by card / I pay by card.

2. zapłacić

This is perfective.

It means:

• to pay as a completed action
• often one payment, one finished act

Example:

• Muszę zapłacić za prąd. = I have to pay for electricity.

3. opłacić

This is also perfective.

It often means:

• to pay for
• to settle
• to cover a charge, fee, bill, subscription, etc.

With rachunki, opłacić is very natural and suggests getting the bills taken care of.

So:

• Muszę opłacić rachunki = I have to pay/settle the bills
• Muszę zapłacić rachunki is also understandable and natural in many contexts

A simple way to remember it:

• płacić = paying in general
• zapłacić = to pay once, successfully
• opłacić = to settle/pay something like bills, fees, charges

Rachunki is in the accusative plural, because it is the direct object of the verb.

You are paying what?
→ rachunki

The singular noun is rachunek.

For this kind of noun, the accusative plural has the same form as the nominative plural:

• nominative plural: rachunki
• accusative plural: rachunki

So in this sentence, rachunki is the correct object form.

Rachunki is plural.

• singular: rachunek
• plural: rachunki

In this sentence, it means bills.

The singular rachunek can mean several things depending on context, such as:

• a bill
• a check at a restaurant
• an invoice
• an account
• even a calculation in some contexts

But here, rachunki most naturally means bills, especially household or regular bills.

A rough English-friendly pronunciation is:

MOO-sheh o-PWA-cheech ra-HOON-kee

A few pronunciation notes:

• sz sounds like English sh
• ł sounds like English w
• ć / ci is a soft sound, somewhat like a very soft ch
• ch in rachunki is like the sound in Scottish loch or German Bach
• ę in muszę is nasal, but at the end of a word it is often pronounced more weakly in everyday speech

Stress in Polish is usually on the second-to-last syllable:

• MU-szę
• o-PŁA-cić
• ra-CHUN-ki

No. Rachunek / rachunki can mean different things depending on context.

Possible meanings include:

• bills
• invoices
• checks
• accounts
• calculations

But in Muszę opłacić rachunki, the meaning is very likely bills, especially things like:

• electricity
• gas
• rent-related charges
• internet
• phone bills

So the context strongly points to paying bills.

Grammatically, muszę is present tense.

But the whole sentence usually refers to something that still needs to be done, often now or soon.

So in English, it is best translated as something like:

• I have to pay the bills
• I need to pay the bills

Because opłacić is perfective, it focuses on the action being completed.
So the sense is not I am paying the bills right now, but rather I need to get the bills paid.

The natural negative version is:

Nie muszę opłacać rachunków.

This means:

I don’t have to pay the bills.

There are two important changes here:

1. muszę → nie muszę

That gives you I don’t have to

2. opłacić → opłacać

With nie muszę, the imperfective infinitive is often more natural.

3. rachunki → rachunków

After negation, Polish often uses the genitive instead of the accusative.

So:

• positive: Muszę opłacić rachunki.
• negative: Nie muszę opłacać rachunków.

This is a very useful pattern to learn early.