Learn Hardcore Spanish (Spain): No quiero pedir un préstamo grande si luego no puedo pagar la deuda. - I don’t want to take out a big loan if later I can’t pay the debt.

solicitar un préstamo – more formal, very common in banking or written language.
sacar un préstamo – heard in some regions, but pedir un préstamo is the safest, most standard choice in Spain.

So No quiero pedir un préstamo grande… is exactly how a Spaniard would normally say I don’t want to take out a big loan…

What’s the difference between un préstamo grande, un gran préstamo, and un grande préstamo?

grande changes meaning and form depending on its position:

After the noun:
- un préstamo grande = a big loan (large amount of money).
- Here it’s about size/quantity, literal bigness.
Before the noun (shortened):
- un gran préstamo (not un grande préstamo) = literally a great loan.
- More figurative: a great loan, maybe very advantageous or important, not simply large in amount.
*un grande préstamo is incorrect.
- Before a singular noun, grande must shorten to gran: gran préstamo, gran casa, gran idea.

In this sentence we want to emphasize the amount of money, so un préstamo grande is the natural choice.

What exactly does luego mean here, and can it be left out or replaced by después?

Here luego means later / afterwards / then in a time sequence:

…si luego no puedo pagar la deuda ≈ if later I can’t pay back the debt / if I then can’t pay the debt.

About alternatives:

You can omit it:
- …si no puedo pagar la deuda.
- This is perfectly correct and a bit more direct. luego just makes the temporal sequence more explicit.
You can replace it with después:
- …si después no puedo pagar la deuda.
- Also fine; in Spain, luego here sounds very natural and maybe a bit more conversational.

So luego is optional and mainly highlights that the problem comes afterwards, as a consequence in time of taking the loan.

Why is it no quiero pedir and not something like no quiero que pido/pida?

In Spanish, when the same person is both the one who doesn’t want and the one who would do the action, you normally use querer + infinitive:

No quiero pedir un préstamo.
= I don’t want to ask for a loan (I would be the one asking).

No quiero que… is used when a different subject does the second action:

No quiero pedir un préstamo.
I don’t want to ask for a loan (I am the one asking).
No quiero que pidan un préstamo.
I don’t want them to ask for a loan.

So no quiero pedir is the correct structure here, since I don’t want to ask.

Why is puedo in the present tense instead of a future form like podré?

Spanish normally does not use the future tense after “si” (if) in this kind of condition. Instead, it uses the present indicative, even for future time:

Si luego no puedo pagar la deuda…
Literally: If later I can’t pay the debt…
Meaning in real life: If later I won’t be able to pay it…

Using podré in the si-clause (*si luego no podré pagar) is generally incorrect or at least very unnatural in standard Spanish.

Typical pattern:

Si tengo tiempo, te llamaré.
If I have time, I’ll call you.
(present in the si-clause, future in the main clause)

In our sentence, the main clause is also in the present (no quiero…) because the speaker is stating their current intention. The si-clause uses present (puedo) to talk about a possible future situation.

Why is it no puedo pagar (indicative) and not no pueda pagar (subjunctive) after si?

With si meaning if in a straightforward conditional sentence, Spanish usually uses the indicative, not the subjunctive:

Si luego no puedo pagar la deuda… (normal, neutral)
*Si luego no pueda pagar la deuda… (wrong in standard usage)

Subjunctive after si appears in other, more special structures (e.g. si bien, como si), but for basic if X, then Y conditions, si + indicative is the rule.

There is a subjunctive conditional pattern:

Si luego no pudiera pagar la deuda, sería un problema.
If later I couldn’t pay the debt, it would be a problem.

Here:

pudiera = past subjunctive
sería = conditional

This sounds more hypothetical and less immediate. In your original sentence, the speaker is talking about a real, concrete possibility, so indicative: no puedo pagar is correct.

Why do we say pagar la deuda and not just pagar deuda?

In Spanish, a singular, countable noun like deuda (debt) almost always needs an article or a determiner:

pagar la deuda – pay the debt.
pagar una deuda – pay a debt.
pagar mis deudas – pay my debts.

Bare pagar deuda sounds wrong, except in some fixed expressions or very technical/business jargon.

Here, la deuda is specific: it refers to the particular debt created by that big loan, so the definite article la is the natural choice.

Could we say pagar el préstamo or devolver el préstamo instead of pagar la deuda?

Yes, both are possible, but they shift the nuance slightly:

pagar la deuda
Focus on the debt itself (the money owed). Very common in everyday speech.
pagar el préstamo
Focus more directly on the loan as a product/contract. Also fine.
devolver el préstamo
Literally to return the loan, i.e. to pay back / repay the loan. Very natural when you talk specifically about repaying the borrowed sum.

So you could say:

No quiero pedir un préstamo grande si luego no puedo devolverlo.
…si luego no puedo pagar el préstamo.

The original pagar la deuda sounds very normal and slightly more general.

Why la deuda instead of mi deuda (“my debt”)?

Spanish often uses the definite article where English uses a possessive, especially when the possessor is clear from context:

Me duele la cabeza. = My head hurts.
Se lavó las manos. = He washed his hands.
Pagar la deuda. = Pay the debt (my debt, the one we’re talking about).

In your sentence, it’s obvious that the debt belongs to the speaker (it’s the debt from their loan), so la deuda is enough. mi deuda would sound a bit heavier and is only needed if you really want to emphasize “my (as opposed to someone else’s) debt”.

Can we replace pagar la deuda with pagarla? Where does the pronoun go?

Yes, you can replace la deuda with the direct object pronoun la:

Two correct options here:

Before the conjugated verb:
- …si luego no la puedo pagar.
Attached to the infinitive:
- …si luego no puedo pagarla.

Both are fully correct and natural. With poder + infinitive, pronouns can either:

come before the conjugated verb (la puedo pagar), or
attach to the infinitive (pagarla).

So your whole sentence could be:

No quiero pedir un préstamo grande si luego no puedo pagarla.
No quiero pedir un préstamo grande si luego no la puedo pagar.

Where does no go in the sentence, and could it appear somewhere else?

The negative no always goes directly before the conjugated verb it negates:

No quiero pedir… (negates quiero)
…si luego no puedo pagar… (negates puedo)

You can’t move no to the end or separate it from the verb:

*Quiero no pedir un préstamo grande… – grammatically possible but changes the meaning to I want not to ask for… (odd here).
*Si luego puedo no pagar la deuda. – would mean If later I am able not to pay the debt, i.e. “if I can avoid paying”, which is not the same idea.

For simple negation, just put no immediately before the conjugated verb you want to negate, as in the original sentence.

Is this sentence particularly natural in Spain, and are there alternative ways a Spaniard might say the same idea?

The sentence is very natural for European Spanish as is. A Spaniard might also say things like:

No quiero pedir un préstamo tan grande si luego no voy a poder pagarlo.
No me quiero meter en un préstamo tan grande si luego no puedo hacer frente a la deuda.
No quiero endeudarme tanto si luego no voy a poder pagar.

Notes:

tan grande = so big / that big, adds emphasis.
no voy a poder = I’m not going to be able to (slightly more explicit future meaning).
hacer frente a la deuda = to face / meet / service the debt, a common idiom in Spain.
endeudarme = to get into debt.

Your original sentence is already perfectly idiomatic in Spain.