Learn Hardcore Ukrainian: Я маю заплатити карткою, бо не маю готівки. - I have to pay by card because I do not have cash.

It expresses obligation: я маю заплатити = “I have to pay.” This use of мати as a modal (“to have to”) is very common in everyday Ukrainian. In more formal writing, people often prefer other options like повинен/повинна or треба.

Could I say мені треба/я мушу/я повинен(-на) заплатити instead? What’s the difference?

Yes, all are correct, with nuances:

мені треба заплатити — impersonal necessity (“it’s necessary for me”).
я мушу заплатити — strong necessity/urgency (“I must”).
я повинен заплатити (masc.) / я повинна заплатити (fem.) — duty/obligation, more formal.
я маю заплатити — very common in speech; neutral in tone but slightly colloquial in some regions/registers.

Why is it заплатити (perfective) and not платити (imperfective)?

Because it’s a single, completed act of payment. Use:

заплатити for one completed payment (now or in the future): Я маю заплатити; Я заплачу карткою.
платити for process/habit: Я зазвичай плачу карткою (“I usually pay by card”).

What complements go with заплатити?

Typical patterns:

For what? — заплатити за щось: заплатити за каву.
With what? (means) — instrumental: заплатити карткою/готівкою/Apple Pay.
To whom? — dative: заплатити продавцеві/офіціантці. Also related verbs: оплатити рахунок, сплатити податки, розрахуватися карткою.

Why is it карткою and not картку?

Payment method is expressed with the instrumental case (answering “with what?”): карткою. Using картку would make “card” a direct object, which is not what you mean here (you’re not paying the card; you’re paying with it). For feminine nouns ending in -ка, the instrumental singular is typically -кою: картка → карткою.

Is картка the right word? What about карта or карточка?

картка is the standard word for bank/ID cards: банківська картка, кредитна/дебетова картка.
карта mainly means “map” (also “playing card”), so картою would sound like “by a map.”
карточка is a Russianism; avoid it in standard Ukrainian. Colloquially, you may hear кредиткою (“with a credit card”), but the neutral form is кредитною карткою.

Why is it готівки and not готівку?

Because of the genitive of negation. With transitive verbs in the negative, Ukrainian often uses the genitive to stress absence:

Affirmative: маю готівку (“I have cash”) — accusative.
Negative: не маю готівки (“I don’t have cash”) — genitive.

Can I say У мене немає готівки instead of Я не маю готівки?

Yes, both are natural:

Я не маю готівки — “I don’t have cash.”
У мене немає готівки — literally “At me there is no cash,” very common. Notes:
немає is one word; a colloquial short form is нема.
в/у мене: choose в or у for euphony (here у мене is smoother).

Can I drop я or change the word order?

Yes. Ukrainian often drops the subject pronoun if the verb form makes it clear:

Маю заплатити карткою, бо не маю готівки. You can also add я for emphasis or clarity:
…бо я не маю готівки. Word order is flexible for emphasis: …бо готівки не маю stresses the “no cash” part.

Is бо the same as тому що? What about punctuation?

бо and тому що both mean “because.” бо is shorter and very common in speech; тому що is fully neutral; оскільки is more formal; адже adds “after all/you know.”
Put a comma before them: …, бо … / …, тому що ….

How do I pronounce and stress the sentence?

Stresses:

Я ма́ю заплати́ти ка́рткою, бо не ма́ю готі́вки. Rough guide: [ya MA-yu zapla-TY-ty KART-ko-yu, bo ne MA-yu ho-TIV-ky]. Keep the “тк” cluster in карткою clear.

Is it correct to write немаю as one word?

No. Write не маю (two words). But немає is one word (3rd person), and нема is a colloquial short form. So:

Я не маю готівки.
У мене немає готівки.

What are other natural ways to say “pay by card”?

розрахуватися карткою (very common at restaurants/shops)
оплатити рахунок карткою
здійснити оплату карткою (formal) All use instrumental карткою for the payment method.

How would I say I usually pay by card?

Use the imperfective for a habit: Я зазвичай плачу карткою. Note: плачу can also mean “I cry”; the forms are identical, but context makes it clear.